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Sample records for 4-nitroquinoline 1-oxide 4nqo

  1. The effect of vitamin C on the hamster cheek pouch treated with the water soluble carcinogen 4-nitroquinoline-1-oxide (4NQO).

    PubMed

    Kandarkar, S V; Sawant, S S

    1996-07-01

    Vitamin C is an essential nutrient whose protective influence is carcinogenesis has been reported frequently, suggesting that vitamin C inhibits the formation of some carcinogens and decreases the incidence and delays of the neoplastic lesions. However, the mechanisms by which this occurs are unknown. In this study, the water soluble carcinogen 4-nitroquinoline-1-oxide (4NQO) has been used to induce a high yield of tumours in the oral cavity either singly or in combination with tobacco. Since the mucosa of rats is less susceptible to carcinogens than the hamster cheek pouch, the hamster cheek pouch has been used to study the influence of vitamin C on 4NQO-induced oral malignancy. The aim of this study was to determine whether topically applied vitamin C had an effect on the oral carcinogenesis induced by application of 4NQO. Similarly, an attempt was made to study the modulating effect of vitamin C on the histopathological and ultrastructural changes during the neoplastic process in the hamster. Vitamin C appeared to delay tumour induction and had other protective effects against neoplasia. PMID:8776418

  2. 4-nitroquinoline-1-oxide induced experimental oral carcinogenesis.

    PubMed

    Kanojia, Deepak; Vaidya, Milind M

    2006-08-01

    Human oral cancer is the sixth largest group of malignancies worldwide and single largest group of malignancies in the Indian subcontinent. Seventy percent of premalignant cancers appear from premalignant lesions. Only 8-10% of these lesions finally turn into malignancy. The appearance of these premalignant lesions is one distinct feature of human oral cancer. At present there is dearth of biomarkers to identify which of these lesions will turn into malignancy. Regional lymph node metastasis and locoregional recurrence are the major factors responsible for the limited survival of patients with oral cancer. Paucity of early diagnostic and prognostic markers is one of the contributory factors for higher mortality rates. Cancer is a multistep process and because of constrain in availability of human tissues from multiple stages of oral carcinogenesis including normal tissues, animal models are being widely used, aiming for the development of diagnostic and prognostic markers. A number of chemical carcinogens like coal tar, 20 methyl cholanthrene (20MC), 9,10-dimethyl-1,2-benzanthracene (DMBA) and 4-nitroquinoline-1-oxide (4NQO) have been used in experimental oral carcinogenesis. However, 4NQO is the preferred carcinogen apart from DMBA in the development of experimental oral carcinogenesis. 4NQO is a water soluble carcinogen, which induces tumors predominantly in the oral cavity. It produces all the stages of oral carcinogenesis and several lines of evidences suggest that similar histological as well as molecular changes are observed in the human system. In the present review an attempt has been made to collate the information available on mechanisms of action of 4NQO, studies carried out for the development of biomarkers and chemopreventives agents using 4NQO animal models. PMID:16448841

  3. 4-Nitroquinoline-1-oxide effects human lung adenocarcinoma A549 cells by regulating the expression of POLD4

    PubMed Central

    HUANG, QIN-MIAO; ZENG, YI-MING; ZHANG, HUA-PING; LV, LIANG-CHAO; YANG, DONG-YONG; LIN, HUI-HUANG

    2016-01-01

    The aim of the present study was to explore the expression of POLD4 in human lung adenocarcinoma A549 cells under 4-nitroquinoline-1-oxide (4NQO) stimulation to investigate the role of POLD4 in smoking-induced lung cancer. The lung cancer A549 cell line was treated with 4NQO, with or without MG132 (an inhibitor of proteasome activity), and subsequently the POLD4 level was determined by western blot analysis. Secondly, the cell sensitivity to 4NQO and Taxol was determined when the POLD4 expression level was downregulated by siRNA. The POLD4 protein levels in the A549 cells decreased following treatment with 4NQO; however, MG132 could reverse this phenotype. Downregulation of the POLD4 expression by siRNA enhanced A549 cell sensitivity to 4NQO, but not to Taxol. In conclusion, 4NQO affects human lung adenocarcinoma A549 cells by regulating the expression of POLD4. PMID:26998273

  4. 4-nitroquinoline-1-oxide-induced mutagen sensitivity and risk of cutaneous melanoma: a case-control analysis.

    PubMed

    Wang, Li-E; Li, Chunying; Xiong, Ping; Gershenwald, Jeffrey E; Prieto, Victor G; Duvic, Madeleine; Lee, Jeffrey E; Grimm, Elizabeth A; Hsu, Tao C; Wei, Qingyi

    2016-04-01

    Mutagen sensitivity assay, which measures the enhanced cellular response to DNA damage induced in vitro by mutagens/carcinogens, has been used in the study of cancer susceptibility. 4-Nitroquinoline-1-oxide (4-NQO), an ultraviolet (UV) radiation-mimetic chemical, can produce chromosomal breaks in mammalian cells and induce cancer. Given the potential role of 4-NQO as the experimental mutagen substituting for UV as the etiological carcinogen of cutaneous melanoma (CM), we tested the hypothesis that cellular sensitivity to 4-NQO is associated with the risk of developing CM in a case-control study of 133 patients with primary CM and 176 cancer-free controls. Short-term blood cultures were treated with 4-NQO at a final concentration of 10 μmol/l for 24 h and scored chromatid breaks in 50 well-spread metaphases. Multivariate logistic regression was used to calculate odds ratios and 95% confidence intervals. We found that the log-transformed frequency of chromatid breaks was significantly higher in 133 patients than in 176 controls (P=0.004) and was associated with an increased risk for CM (adjusted odds ratio=1.78, 95% confidence interval: 1.12-2.84) after adjustment for age and sex. Moreover, as the chromatid break values increased, the risk for CM increased in a dose-dependent manner (P(trend)=0.003). Further analysis explored a multiplicative interaction between the sensitivity to 4-NQO and a family history of skin cancer (P(interaction)=0.004) on the risk of CM. Therefore, our findings suggest that sensitivity to 4-NQO may be a risk factor for the risk of CM, which is more sensitive than UV-induced chromotid breaks.

  5. 4-Nitroquinoline-1-oxide-induced mutagen sensitivity and risk of cutaneous melanoma: a case–control analysis

    PubMed Central

    Wang, Li-E; Li, Chunying; Xiong, Ping; Gershenwald, Jeffrey E.; Prieto, Victor G.; Duvic, Madeleine; Lee, Jeffrey E.; Grimm, Elizabeth A.; Hsu, T.C.; Wei, Qingyi

    2016-01-01

    Mutagen sensitivity assay, which measures the enhanced cellular response to DNA damage induced in vitro by mutagens/carcinogens, has been used in the study of cancer susceptibility. 4-Nitroquinoline-1-oxide (4-NQO), an ultraviolet (UV) radiation-mimetic chemical, can produce chromosomal breaks in mammalian cells and induce cancer. Given the potential role of 4-NQO as the experimental mutagen substituting for UV as the etiological carcinogen of cutaneous melanoma (CM), we tested the hypothesis that cellular sensitivity to 4-NQO is associated with the risk of developing CM in a case–control study of 133 patients with primary CM and 176 cancer-free controls. Short-term blood cultures were treated with 4-NQO at a final concentration of 10 µmol/l for 24 h and scored chromatid breaks in 50 well-spread metaphases. Multivariable logistic regression was used to calculate odds ratios and 95% confidence intervals. We found that the log-transformed frequency of chromatid breaks was significantly higher in 133 patients than in 176 controls (P = 0.004) and was associated with an increased risk for CM (adjusted odds ratio = 1.78, 95% confidence interval: 1.12–2.84) after adjustment for age and sex. Moreover, as the chromatid break values increased, the risk for CM increased in a dose-dependent manner (Ptrend = 0.003). Further analysis explored a multiplicative interaction between the sensitivity to 4-NQO and a family history of skin cancer (Pinteraction = 0.004) on the risk of CM. Therefore, our findings suggest that sensitivity to 4-NQO may be a risk factor for the risk of CM, which is more sensitive than UV-induced chromosome breaks. PMID:24977319

  6. In-vivo Antioxidant Effects of Ethyl Acetate Fraction of Mentha spicata L. on 4-Nitroquinoline-1-Oxide Injected Mice.

    PubMed

    Arumugam, Ponnan; Ramesh, Arabandi

    2011-01-01

    Antioxidant effects of ethyl acetate fraction of Mentha spicata (L.) were evaluated against 4-nitroquinoline-1-oxide injected mice. For this study, experiment setup consisted of 36 albino mice of either sex divided into 6 groups: Control (25% DMSO in water), ethyl acetate fraction (EAF) alone group (80, 160 mg/Kg body weight-bwt), 4-NQO (7.5 mg/Kg bwt-IP) alone and 4-NQO + EAF. EAF and vehicles were administered orally for five consecutive days. 4-NQO (7.5 mg/Kg bwt) was injected intraperitoneally on the 6(th) day. After 24 h, the animals were killed; liver sample was extracted and used for bio-assay. 4-NQO alone treated group decreased (27-60%) the antioxidant activities and promoted lipid peroxidation (LPO-60%) over their respective control values. Pretreatment with EAF, at the maximum dose (160 mg/Kg bwt) brought down the LPO up to 87% enhanced by 4-NQO. Among the enzymatic antioxidants, glutathione S-transferase (GST) was the most affected enzyme with 4-NQO and the least was catalase (CAT). Pretreatment with EAF (160 mg/Kg bwt), the restoration of antioxidants like glutathione peroxidase, superoxide dismutase, and CAT were found equal or less than 1.2 fold higher than that of the respective control values whereas, GST was observed to be the most restored antioxidant. Be reduced glutathione (GSH) and the least vitamin C over their control values. EAF restored the GSH and Vitamin E levels were found to be 1.2 fold higher than the respective control values.

  7. Combination of bexarotene and the retinoid CD1530 reduces murine oral-cavity carcinogenesis induced by the carcinogen 4-nitroquinoline 1-oxide

    PubMed Central

    Tang, Xiao-Han; Osei-Sarfo, Kwame; Urvalek, Alison M.; Zhang, Tuo; Scognamiglio, Theresa; Gudas, Lorraine J.

    2014-01-01

    We investigated the effects of bexarotene (a retinoid X receptor agonist), CD1530 (a retinoic acid receptor γ selective agonist), and the combination of these two drugs for the prevention of oral carcinogenesis induced by the carcinogen 4-nitroquinoline 1-oxide (4-NQO) in a mouse model of human oral-cavity and esophageal squamous-cell carcinoma previously generated in our laboratory. We observed decreased numbers of neoplastic tongue lesions and reduced lesion severity in the 4-NQO plus CD1530 (4N+C) and 4-NQO plus bexarotene plus CD1530 (4N+B+C) groups compared with the 4-NQO group. RNA-Seq analyses showed increases in transcripts in cell proliferation/cell cycle progression pathways in the 4-NQO vs. the untreated group. In addition, β-catenin and matrix metallopeptidase 9 (MMP9) protein levels and reactive oxygen species (ROS), as assessed by 4-hydroxynonenal (4-HNE) staining, were elevated in tongue tissues 17 wk after the termination of the 4-NQO treatment. The 4N+B, 4N+C, and 4N+B+C groups showed dramatically lower levels of β-catenin, MMP9, and 4-HNE staining compared with the 4-NQO group. The major reduction in 4-HNE staining in the retinoid treatment groups suggests a novel mechanism of action, reduction of ROS, by which bexarotene and CD1530 inhibit carcinogenesis. PMID:24927566

  8. Identification of Ethanol and 4-Nitroquinoline-1-Oxide Induced Epigenetic and Oxidative Stress Markers During Oral Cavity Carcinogenesis

    PubMed Central

    Urvalek, Alison M.; Osei-Sarfo, Kwame; Tang, Xiao-Han; Zhang, Tuo; Scognamiglio, Theresa; Gudas, Lorraine J.

    2015-01-01

    Background Head and neck squamous cell carcinoma (HNSCC) is a cancer that is characterized by its high morbidity and mortality rates. While tobacco use and alcohol consumption are two major contributing factors for HNSCC carcinogenesis, how the combination of tobacco and alcohol increases HNSCC risk is not understood. Methods We combined the 4-nitroquinoline-1-oxide (4-NQO) oral carcinogenesis and Meadows-Cook alcohol mouse models to elucidate the molecular events and to identify novel biomarkers associated with oral cancer development. Results By genome-wide RNA-seq of tongue samples (three mice per group) we identified changes in transcripts that mediate alcohol metabolism and oxidative stress (Aldh2, Aldh1a3, Adh1, Adh7, and Cyp2a5) in mice treated with 4-NQO followed by ethanol (4-NQO/EtOH) as compared to the vehicle control/untreated samples (V.C./Untr.). We measured major, global increases in specific histone acetylation and methylation epigenetic marks (H3K27ac, H3K9/14ac, H3K27me3, and H3K9me3) in the oral cavities of V.C./EtOH, 4-NQO/Untr. and 4-NQO/EtOH treatment groups compared to the V.C./Untr. group. We detected changes in histone epigenetic marks near regulatory regions of genes involved in ethanol metabolism by chromatin immunoprecipitation (ChIP). For instance, the Aldh2 promoter showed increased H3K27me3 marks, and Aldh2 mRNA levels were reduced by 10-fold in 4NQO/EtOH vs. V.C./Untr. tongue samples. 4-NQO/EtOH treatment also caused increases in markers of oxidative stress, including 4-HNE, MCT4/Slc16a3, and TOM20, as measured by immunohistochemistry. Conclusions We delineate a mechanism by which 4-NQO and ethanol can regulate gene expression during the development of HNSCC, and suggest that histone epigenetic marks and oxidative stress markers could be novel biomarkers and targets for the prevention of HNSCC. PMID:26207766

  9. Cell cycle-related genotoxic effects of 4-nitroquinoline-1-oxide in C3H 10T1/2 cells

    SciTech Connect

    Bentley, K.L.S.

    1985-01-01

    The aim of this study was to determine the cell cycle sensitivity of cell killing, mutation, and neoplastic transformation produced by 4-nitroquinoline-1-oxide (4NQO), a potent mutagen and carcinogen. Studies were performed in populations of 10T1/3 cells synchronized by replacing them to low density after confluence-induced arrest of proliferation. Percent survival (RCFE), the mutation frequency (ouabain resistance), and the transformation frequency (types II and III foci) were independent of the phase of the cell cycle during which the cells were exposed to 4NQO. However, quantities of (/sup 3/H)4NQO bound to the DNA of treated cells were greatest during the G/sub 1/ phase and fell 50% as the cells entered the S phase. 4NQO induced unscheduled DNA synthesis in confluence-arrested cultures, and the cell removed 25% of bound (/sup 3/H)4NQO over a 12 hour post-treatment incubation period when treated either early in the G/sub 1/ phase or at the G/sub 1//S border. These date indicated that 4NQO induced DNA adducts were removed from the DNA Of 10T1/2 cells. DNA replication in 10T1/2 cells was markedly inhibited by 4NQO. Treatment during the G/sub 1/ phase produced delays in the onset of the S phase and a reduction in the rate of subsequent DNA synthesis. A similar decrease in rate was observed for cells exposed to 4NQO in the S phase. The reduced levels of DNA replication were largely due to the decreased number of cells synthesizing DNA. The cycle-independent responses of 10T1/2 cells to 4NQO-induced cytotoxicity, mutation, and neoplastic transformation resulted from the increase in 4NQO bound to DNA during the G/sub 1/ phase and its subsequent removal during the delay of the initiation of DNA replication.

  10. Initiation of esophageal squamous cell carcinoma (ESCC) in a murine 4-nitroquinoline-1-oxide and alcohol carcinogenesis model

    PubMed Central

    Osei-Sarfo, Kwame; Scognamiglio, Theresa; Gudas, Lorraine J.

    2015-01-01

    Esophageal squamous cell carcinomas (ESCCs) are very common, aggressive tumors, and are often associated with alcohol and tobacco abuse. Because ESCCs exhibit high recurrence rates and are diagnosed at late stages, identification of prognostic and drug targets for prevention and treatment is critical. We used the 4-nitroquinoline-1-oxide (4-NQO) murine model of oral carcinogenesis and the Meadows-Cook model of alcohol abuse to assess changes in the expression of molecular markers during the initial stages of ESCC. Combining these two models, which mimic chronic alcohol and tobacco abuse in humans, we detected increased cellular proliferation (EGFR and Ki67 expression), increased canonical Wnt signaling and downstream elements (β-catenin, FoxM1, and S100a4 protein levels), changes in cellular adhesive properties (reduced E-cadherin in the basal layer of the esophageal epithelium), and increased levels of phosphorylated ERK1/2 and p38. Additionally, we found that treatment with ethanol alone increased the numbers of epithelial cells expressing solute carrier family 2 (facilitated glucose transporter, member 1) (SLC2A1) and carbonic anhydrase IX (CAIX), and increased the phosphorylation of p38. Thus, we identified both 4-NQO- and ethanol-specific targets in the initial stages of esophageal carcinogenesis, which should lead to the development of potential markers and therapeutic targets for human ESCC. PMID:25714027

  11. Protective effects of solvent fractions of Mentha spicata (L.) leaves evaluated on 4-nitroquinoline-1-oxide induced chromosome damage and apoptosis in mouse bone marrow cells.

    PubMed

    Arumugam, Ponnan; Ramesh, Arabandi

    2009-10-01

    Spearmint leaves (Mentha spicata L.) contain high levels of antioxidants that are known to protect against both exogenous and endogenous DNA damage. In this study, the protective effects of the hexane fraction (HF), chloroform fraction (CF) and ethyl acetate fraction (EAF) in an ethanol extract from M. spicata were evaluated against 4-nitroquinoline-1-oxide (4-NQO) induced chromosome damage and apoptosis in bone marrow cells of Swiss albino mice. Two (EAF; 80 and 160 mg/ kg body weight - bw) or three (HF and CF; 80, 160 and 320 mg/ kg bw) doses of solvent fractions or vehicle control (25% DMSO in water) were administered orally for five consecutive days. Upon the sixth day, 4-NQO was injected intraperitoneally. The animals were killed the following day. Other control groups were comprised of animals treated with either the vehicle control or the various doses of solvent fractions, but with no 4-NQO treatment. 4-NQO induced micro-nucleated polychromatic erythrocytes (MnPCEs) in all the test groups. However, pre-treatment of animals with the solvent fractions significantly reduced the 4-NQO-induced MnPCEs as well as the percentage of apoptotic cells. The reduction of both MnPCE and apoptosis was more evident following the pre-treatment of animals with 160 mg/kg bw EAF.

  12. The molecular features of tongue epithelium treated with the carcinogen 4-nitroquinoline-1-oxide and alcohol as a model for HNSCC

    PubMed Central

    Gudas, Lorraine J.

    2013-01-01

    Head and neck squamous cell carcinoma (HNSCC) is the sixth most common type of cancer affecting humans worldwide. To determine the potential mechanisms by which chronic tobacco and alcohol abuse lead to HNSCC of the oral cavity, we have used both the 4-nitroquinoline-1-oxide (4-NQO) murine oral carcinogenesis and the Meadows–Cook alcohol models. In this study, we treated mice with 4-NQO in drinking water for 10 weeks and then administered 20% (w:v) ethanol (EtOH) for another 10 weeks. We observed increased levels and/or activation of signaling proteins [p38 mitogen-activated protein kinase (MAPK), β-catenin and Erk 1/2] that are typically altered during HNSCC initiation in humans. We found that EtOH administration alone increased the expression of p38 MAPK but not Erk 1/2 MAPK. Total β-catenin levels in the tongues increased by 2- to 3-fold after 4-NQO treatment, with or without EtOH. However, EtOH combined with 4-NQO reduced phosphorylated β-catenin levels, whereas 4-NQO treatment alone did not. These data implicate EtOH as a regulator of β-catenin signaling in this HNSCC model. We also utilized K14-CreERTAM; ROSA26 mice to mark permanently stem/progenitor cells in the tongue epithelia. We found that 4-NQO alone and 4-NQO plus EtOH treatment resulted in massive, horizontal expansion of stem/progenitor cell populations arising from single stem cells in the basal layer of the epithelia. This expansion is consistent with carcinogen-associated, symmetric division of stem/progenitor cells. Our data suggest that specific therapeutic targets for prevention of HNSCC of the oral cavity associated with both alcohol and tobacco use are p38 MAPK and β-catenin. PMID:23784083

  13. Abnormal responses to the carcinogen 4-nitroquinoline 1-oxide of cultured fibroblasts from patients with dysplastic nevus syndrome and hereditary cutaneous malignant melanoma

    SciTech Connect

    Smith, P.J.; Greene, M.H.; Adams, D.; Paterson, M.C.

    1983-01-01

    The dysplastic nevus syndrome (DNS) is a preneoplastic melanocyte abnormality which occurs in families affected by hereditary cutaneous malignant melanoma (HCMM). A putative role of host-environmental interactions in the etiology of hereditary melanoma has been strengthened by the recent finding that fibroblasts derived from HCMM/DNS patients demonstrated enhanced sensitivity to u.v.-irradiation in vitro. An extension of these studies is reported in which we have examined the invitro responses to a model environmental carcinogen, 4-nitroquinoline 1-oxide (4NQO), of six non-tumor skin fibroblast strains from HCMM/DNS patients representing five families. Three of the six HCMM/DNS strains showed enhanced cell killing with sensitivities greater than that of a xeroderma pigmentosum (XP) variant strain but less than those of ataxia telangiectasia and XP Group D cell strains. The inhibition and recovery of de novo DNA synthesis, together with the expression of repair synthesis, following 4NQO exposure appeared to be normal in HCMM/DNS strains, irrespective of their subsequent clonogenic potential. The data point to a metabolic anomaly which may contribute to the carcinogenic risk of the melanoma prone preneoplastic state presented by some DNS patients.

  14. Early induction of cytokines/cytokine receptors and Cox2, and activation of NF-κB in 4-nitroquinoline 1-oxide-induced murine oral cancer model

    SciTech Connect

    Liu, Yu-Ching; Ho, Heng-Chien; Lee, Miau-Rong; Lai, Kuang-Chi; Yeh, Chung-Min; Lin, Yueh-Min; Ho, Tin-Yun; Hsiang, Chien-Yun; Chung, Jing-Gung

    2012-07-15

    The purpose of this study was to identify the genes induced early in murine oral carcinogenesis. Murine tongue tumors induced by the carcinogen, 4-nitroquinoline 1-oxide (4-NQO), and paired non-tumor tissues were subjected to microarray analysis. Hierarchical clustering of upregulated genes in the tumor tissues revealed an association of induced genes with inflammation. Cytokines/cytokine receptors induced early were subsequently identified, clearly indicating their involvement in oral carcinogenesis. Hierarchical clustering also showed that cytokine-mediated inflammation was possibly linked with Mapk6. Cox2 exhibited the greatest extent (9–18 fold) of induction in the microarray data, and its early induction was observed in a 2 h painting experiment by RT-PCR. MetaCore analysis showed that overexpressed Cox2 may interact with p53 and transcriptionally inhibit expression of several downstream genes. A painting experiment in transgenic mice also demonstrated that NF-κB activates early independently of Cox2 induction. MetaCore analysis revealed the most striking metabolic alterations in tumor tissues, especially in lipid metabolism resulting from the reduction of Pparα and Rxrg. Reduced expression of Mapk12 was noted, and MetaCore analysis established its relationship with decreased efficiency of Pparα phosphorylation. In conclusion, in addition to cytokines/cytokine receptors, the early induction of Cox2 and NF-κB activation is involved in murine oral carcinogenesis.

  15. Genotoxicity studies of organically grown broccoli (Brassica oleracea var. italica) and its interactions with urethane, methyl methanesulfonate and 4-nitroquinoline-1-oxide genotoxicity in the wing spot test of Drosophila melanogaster.

    PubMed

    Heres-Pulido, María Eugenia; Dueñas-García, Irma; Castañeda-Partida, Laura; Santos-Cruz, Luis Felipe; Vega-Contreras, Viridiana; Rebollar-Vega, Rosa; Gómez-Luna, Juan Carlos; Durán-Díaz, Angel

    2010-01-01

    Broccoli (Brassica oleracea var. italica) has been defined as a cancer preventive food. Nevertheless, broccoli contains potentially genotoxic compounds as well. We performed the wing spot test of Drosophila melanogaster in treatments with organically grown broccoli (OGB) and co-treatments with the promutagen urethane (URE), the direct alkylating agent methyl methanesulfonate (MMS) and the carcinogen 4-nitroquinoline-1-oxide (4-NQO) in the standard (ST) and high bioactivation (HB) crosses with inducible and high levels of cytochrome P450s (CYPs), respectively. Larvae of both crosses were chronically fed with OGB or fresh market broccoli (FMB) as a non-organically grown control, added with solvents or mutagens solutions. In both crosses, the OGB added with Tween-ethanol yielded the expected reduction in the genotoxicity spontaneous rate. OGB co-treatments did not affect the URE effect, MMS showed synergy and 4-NQO damage was modulated in both crosses. In contrast, FMB controls produced damage increase; co-treatments modulated URE genotoxicity, diminished MMS damage, and did not change the 4-NQO damage. The high dietary consumption of both types of broccoli and its protective effects in D. melanogaster are discussed.

  16. The ultimate carcinogen of 4-nitroquinoline 1-oxide does not react with Z-DNA and hyperreacts with B-Z junctions.

    PubMed Central

    Rodolfo, C; Lanza, A; Tornaletti, S; Fronza, G; Pedrini, A M

    1994-01-01

    DNA secondary and tertiary structures are known to affect the reaction between the double helix and several damaging agents. We have previously shown that the tertiary structure of DNA influences the reactivity of 4-acetoxyaminoquinoline 1-oxide (Ac-4-HAQO), the ultimate carcinogen of 4-nitroquinoline 1-oxide (4-NQO), being more reactive with naturally supercoiled DNA than with relaxed DNA. The relative proportion of the three main stable adducts and of an unstable adduct, that resulted in strand scission and/or AP sites, was also affected by the degree of supercoiling of plasmid DNA. In this study we examined the influence of Z-DNA structure on the reactivity of Ac-4-HAQO by mapping the distribution of the two main Ac-4-HAQO adducts, C8-guanine and N2-guanine, along a (dC-dG)16 sequence inserted at the BamHI site of pBR322 plasmid DNA. This insert adopted the left-handed Z and right-handed B structure depending on the superhelical density of the plasmid. Sites of C8-guanine adduct formation were determined by hot piperidine cleavage of Ac-4-HAQO modified DNA, while N2-guanine adducts were mapped by the arrest of the 3'-5' exonuclease activity of T4 DNA polymerase. The results showed that Ac-4-HAQO did not react with guanine residues when the (dC-dG)16 sequence was in Z conformation, while hyperreactivity at the B-Z junction was observed. These results indicate that Ac-4-HAQO can probe the polymorphism of DNA at the nucleotide level. Images PMID:8127667

  17. Evaluation of in vivo genotoxicity induced by N-ethyl-N-nitrosourea, benzo[a]pyrene, and 4-nitroquinoline-1-oxide in the Pig-a and gpt assays.

    PubMed

    Horibata, Katsuyoshi; Ukai, Akiko; Kimoto, Takafumi; Suzuki, Tetsuya; Kamoshita, Nagisa; Masumura, Kenichi; Nohmi, Takehiko; Honma, Masamitsu

    2013-12-01

    The recently developed Pig-a mutation assay is based on flow cytometric enumeration of glycosylphosphatidylinositol (GPI) anchor-deficient red blood cells caused by a forward mutation in the Pig-a gene. Because the assay can be conducted in nontransgenic animals and the mutations accumulate with repeat dosing, we believe that the Pig-a assay could be integrated into repeat-dose toxicology studies and provides an alternative to transgenic rodent (TGR) mutation assays. The capacity and characteristics of the Pig-a assay relative to TGR mutation assays, however, are unclear. Here, using transgenic gpt delta mice, we compared the in vivo genotoxicity of single oral doses of N-ethyl-N-nitrosourea (ENU, 40 mg/kg), benzo[a]pyrene (BP, 100 and 200 mg/kg), and 4-nitroquinoline-1-oxide (4NQO, 50 mg/kg) in the Pig-a (peripheral blood) and gpt (bone marrow and liver) gene mutation assays. Pig-a assays were conducted at 2, 4, and 7 weeks after the treatment, while gpt assays were conducted on tissues collected at the 7-week terminal sacrifice. ENU increased both Pig-a and gpt mutant frequencies (MFs) at all sampling times, and BP increased MFs in both assays but the Pig-a MFs peaked at 2 weeks and then decreased. Although 4NQO increased gpt MFs in the liver, only weak, nonsignificant increases (two- or threefold above control) were detected in the bone marrow in both the Pig-a and the gpt assay. These findings suggest that further studies are needed to elucidate the kinetics of the Pig-a mutation assay in order to use it as an alternative to the TGR mutation assay.

  18. Therapeutic Efficacy of Orally Delivered Doxorubicin Nanoparticles in Rat Tongue Cancer Induced by 4-Nitroquinoline 1-Oxide

    PubMed Central

    Moradzadeh Khiavi, Monir; Rostami, Ahamd; Hamishekar, Hamed; Mesgari Abassi, Mehran; Aghbali, Amirala; Salehi, Roya; Abdollahi, Bita; Fotoohi, Soheila; Sina, Mahmud

    2015-01-01

    Purpose: Oral cancer is one of the most significant cancers in the world, and squamous cell carcinoma makes up about 94% of oral malignancies. The aim of the present study was to compare the efficacy of doxorubicin plus methotrexate - loaded nanoparticles on tongue squamous cell carcinoma induced by 4NQO and compare it with the commercial doxorubicin and methotrexate delivered orally on seventy SD male rats. Methods: 70 rats were divided into five groups. During the study, the animals were weighed by a digital scale once a week. Number of mortalities was recorded in the data collection forms. At the end of the treatment, biopsy samples were taken from rat tongues in order to evaluate the severity of dysplasia and the extent of cell proliferation. The results were analyzed using ANOVA, descriptive statistics and chi-square test. Results: No statistically significant difference was found in the mean weight of five groups (p>0.05). No significant relationship was found between groups and mortality rate (P = 0. 39). In addition, there was a significant relationship between groups and the degree of dysplasia (P <0.001). The statistical analysis showed a significant relationship between groups and the rate of cell proliferation (p <0.001). Conclusion: The results of the present study showed that the use of doxorubicin plus methotrexate - loaded nanoparticles orally had more therapeutic effects than commercial doxorubicin plus methotrexate. PMID:26236659

  19. Antigenotoxic and antioxidant potential of aqueous fraction of ethanol extract of Mentha spicata (L.) against 4-nitroquinoline-1-oxide-induced chromosome damage in mice.

    PubMed

    Arumugam, Ponnan; Ramesh, Arabandi

    2009-01-01

    The antigenotoxic potential of an aqueous fraction of ethanol extract of Mentha spicata was evaluated by measuring the frequency of micronucleated polychromatic erythrocytes (MnPCEs) in mice bone marrow, using 4-nitroquinoline-1oxide (NQO) as the reference mutagen. In addition, lipid peroxidation (LPO) and antioxidant levels were also quantified with liver tissue of the same mice to assess their antioxidant potential. Swiss albino mice of either sex (25-30 g) were orally pretreated with an aqueous fraction (80, 160, and 320 mg/kg) for 5 consecutive days. NQO (7.5 mg/kg) was injected intraperitoneally after 2 hours until the final day (day 5) of treatment with aqueous fraction. Animals were sacrificed 24 hours later by cervical dislocation and processed for micronuclei and bioassays. A significant reduction (about 67%) of NQO-induced MnPCE frequency was observed at the dose of 320 mg/kg. The LPO was also suppressed effectively, with concomitant changes in both enzymatic and nonenzymatic antioxidants. The restoration level was dose dependent in LPO and glutathione-s-transferase, whereas it was dose independent in superoxide dismutase, glutathione peroxidase, catalase, and reduced glutathione. The results indicate that the aqueous fraction of M. spicata mediates their antigenotoxic effects by the modulation of LPO and antioxidant enzymes.

  20. Head and neck cancer cell lines exhibit differential mitochondrial repair deficiency in response to 4NQO.

    PubMed

    Kim, Michael M; Glazer, Chad A; Mambo, Elizabeth; Chatterjee, Aditi; Zhao, Ming; Sidransky, David; Califano, Joseph A

    2006-02-01

    Constituents of tobacco can cause DNA adduct formation and are implicated in head and neck squamous cell cancer (HNSC) development. We investigated the capacity of HNSC cell lines to repair mitochondrial DNA (mtDNA) damage induced by a DNA adduct-forming agent. HNSC cell lines underwent 4-nitroquinoline 1-oxide (4NQO) exposure with subsequent rescue with normal media. Real-time quantitative PCR for nuclear DNA (nDNA) and mtDNA was performed. mtDNA to nDNA ratios were calculated and standardized to mock-treated cells to assess mtDNA repair ability. Two of three tested cancer cell lines exposed to 4NQO exhibited consistent decreases in mtDNA/nDNA ratios throughout the different repair timepoints. At 24 h mtDNA/nDNA ratios of JHU-O19 and JHU-O22 decreased to 63% and 60% of controls, respectively. Conversely, a control keratinocyte cell line exhibited overall increases in mtDNA/nDNA ratios compared to baseline suggesting intact DNA repair mechanisms. By using a DNA adduct formation and repair model featuring 4NQO and HNSC cell lines, we have implicated faulty mtDNA repair as having a potential role in HNSC.

  1. Inhibition of 4NQO-Induced Oral Carcinogenesis by Dietary Oyster Shell Calcium.

    PubMed

    Chen, Ying; Jiang, Yi; Liao, Liyan; Zhu, Xiaoxin; Tang, Shengan; Yang, Qing; Sun, Lihua; Li, Yujie; Gao, Shuangrong; Xie, Zhongjian

    2016-03-01

    Oyster has gained much attention recently for its anticancer activity but it is unclear whether calcium, the major antitumor ingredient in oyster shell, is responsible for the anticarcinogenic role of the oyster. To address this issue, C57BL/6 mice were fed with the carcinogen 4-nitroquinoline-1-oxide (4NQO, 50 µg/mL) and normal diet or a diet containing oyster powder, oyster calcium, or calcium depleted oyster powder. The tongue tissue specimens isolated from these mice were histologically evaluated for hyperplasia, dysplasia, and papillary lesions, and then analyzed for proliferation and differentiation markers by immunohistochemistry. The results showed that mice on the diet containing oyster calcium significantly reduced rates of tumors in the tongue and proliferation and enhanced differentiation in the oral epithelium compared with the diet containing calcium depleted oyster powder. These results suggest that calcium in oyster plays a critical role in suppressing formation of oral squamous cell carcinoma and proliferation and promoting differentiation of the oral epithelium.

  2. Differential modifying effects of food additive butylated hydroxytoluene toward radiation and 4-nitro-quinoline 1-oxide-induced genotoxicity in yeast.

    PubMed

    Anjaria, Kshiti B; Bhat, Nagesh N; Shirsath, Kapil B; Sreedevi, B

    2011-01-01

    The modifying effect of butylated hydroxytoluene (BHT) on 60Co gamma radiation and 4-nitro-quinoline 1-oxide-induced gene conversion and back mutation frequencies was investigated using diploid yeast Saccharomyces cerevisiae D7. Cells were exposed to 100 or 400 Gy in the presence of 0.025-0.25 mM BHT. BHT exhibited radioprotection and significantly reduced radiation-induced gene conversion and back mutation frequencies as well as cell killing. In another set of experiments, cells were simultaneously treated with 0.025-0.1 mM BHT and 0.5 μM 4-NQO. BHT significantly enhanced 4-NQO-induced gene conversion and back mutation frequencies. BHT post-treatment did not modify radiation-induced genetic events but enhanced 4-NQO-induced back mutation frequencies, indicating its potential to act as a tumor-promoting agent with 4-NQO.

  3. Lactobacillus salivarius REN inhibits rat oral cancer induced by 4-nitroquioline 1-oxide.

    PubMed

    Zhang, Ming; Wang, Fang; Jiang, Lu; Liu, Ruihai; Zhang, Lian; Lei, Xingen; Li, Jiyou; Jiang, Jingli; Guo, Huiyuan; Fang, Bing; Zhao, Liang; Ren, Fazheng

    2013-07-01

    Despite significant advances in cancer therapy, cancer-related mobility and mortality are still rising. Alternative strategies such as cancer prevention thus become essential. Probiotics represent an emerging option for cancer prevention, but studies are limited to colon cancers. The efficiency of probiotics in the prevention of other cancers and the correlative mechanism remains to be explored. A novel probiotics Lactobacillus salivarius REN (L. salivarius REN) was isolated from centenarians at Bama of China, which showed highly potent antigenotoxicity in an initial assay. 4-nitroquioline 1-oxide (4NQO)-induced oral cancer model was introduced to study the anticancer activity of L. salivarius REN in vivo. The results indicated that oral administration of probiotic L. salivarius REN or its secretions could effectively suppress 4NQO-induced oral carcinogenesis in the initial and postinitial stage, and the inhibition was in a dose-dependent manner. A significant decrease of neoplasm incidence (65%-0%) was detected in rats fed with the high dose of L. salivarius REN [5 × 10(10) CFU/kg body weight (bw)/d]. In vivo evidences indicated that the probiotics inhibited 4NQO-induced oral cancer by protecting DNA against oxidative damage and downregulating COX-2 expression. L. salivarius REN treatment significantly decreased the expression of proliferating cell nuclear antigen (PCNA) and induced apoptosis in a dose-dependent manner. Our findings suggest that probiotics may act as potential agents for oral cancer prevention. This is the first report showing the inhibitory effect of the probiotics on oral carcinogenesis. PMID:23658366

  4. Use of high frequency ultrasound to monitor cervical lymph node alterations in mice.

    PubMed

    Walk, Elyse L; McLaughlin, Sarah; Coad, James; Weed, Scott A

    2014-01-01

    Cervical lymph node evaluation by clinical ultrasound is a non-invasive procedure used in diagnosing nodal status, and when combined with fine-needle aspiration cytology (FNAC), provides an effective method to assess nodal pathologies. Development of high-frequency ultrasound (HF US) allows real-time monitoring of lymph node alterations in animal models. While HF US is frequently used in animal models of tumor biology, use of HF US for studying cervical lymph nodes alterations associated with murine models of head and neck cancer, or any other model of lymphadenopathy, is lacking. Here we utilize HF US to monitor cervical lymph nodes changes in mice following exposure to the oral cancer-inducing carcinogen 4-nitroquinoline-1-oxide (4-NQO) and in mice with systemic autoimmunity. 4-NQO induces tumors within the mouse oral cavity as early as 19 wks that recapitulate HNSCC. Monitoring of cervical (mandibular) lymph nodes by gray scale and power Doppler sonography revealed changes in lymph node size eight weeks after 4-NQO treatment, prior to tumor formation. 4-NQO causes changes in cervical node blood flow resulting from oral tumor progression. Histological evaluation indicated that the early 4-NQO induced changes in lymph node volume were due to specific hyperproliferation of T-cell enriched zones in the paracortex. We also show that HF US can be used to perform image-guided fine needle aspirate (FNA) biopsies on mice with enlarged mandibular lymph nodes due to genetic mutation of Fas ligand (Fasl). Collectively these studies indicate that HF US is an effective technique for the non-invasive study of cervical lymph node alterations in live mouse models of oral cancer and other mouse models containing cervical lymphadenopathy. PMID:24955984

  5. Chemopreventive effect of a mixture of Chinese Herbs (antitumor B) on chemically induced oral carcinogenesis.

    PubMed

    Wang, Yian; Yao, Ruisheng; Gao, Song; Wen, Weidong; Du, Yinqiu; Szabo, Eva; Hu, Ming; Lubet, Ronald A; You, Ming

    2013-01-01

    In this study, we evaluated chemopreventive efficacy of Antitumor B, a Chinese herbal mixture of six plants (Sophora tonkinensis, Polygonum bistorta, Prunella vulgaris, Sonchus arvensis L., Dictamnus dasycarpus, and Dioscorea bulbifera) on the development of 4-nitroquinoline-1-oxide (4NQO) induced oral squamous cell carcinomas in A/J mice. Antitumor B, delivered through diet, inhibited 4NQO-induced oral cancer development by 59.19%. The reduction of cell proliferation appears to be associated with efficacy of Antitumor B against 4NQO-induced oral cancer in A/J mice. The expression of epidermal growth factor receptor (EGFR) and phosphorylated EGFR (Tyr1173) were down-regulated by Antitumor B. Tissue distribution of Antitumor B was determined using obacunone, matrine, and maackiain as marker chemicals. We found significant amounts of obacunone, matrine, and maackiain in the blood after 1-wk treatment. The concentrations of these three compounds did not increase further at 18  wk, suggesting that plasma concentrations had reached a steady-state level at 1  wk. There was no significant body weight loss and there was no other obvious sign of toxicity in Antitumor B-treated mice. These results suggest that Antitumor B is a promising agent for human oral cancer chemoprevention. PMID:22086836

  6. Exploring Synergy between Classic Mutagens and Antibiotics To Examine Mechanisms of Synergy and Antibiotic Action

    PubMed Central

    Song, Lisa Yun; D'Souza, Sara; Lam, Karen; Kang, Tina Manzhu

    2015-01-01

    We used classical mutagens in Gram-negative Escherichia coli to study synergies with different classes of antibiotics, test models of antibiotic mechanisms of action, and examine the basis of synergy. We used 4-nitroquinoline 1-oxide (4NQO), zebularine (ZEB), 5-azacytidine (5AZ), 2-aminopurine (2AP), and 5-bromodeoxyuridine (5BrdU) as mutagens (with bactericidal potency of 4NQO > ZEB > 5AZ > 2AP > 5BrdU) and vancomycin (VAN), ciprofloxacin (CPR), trimethoprim (TMP), gentamicin (GEN), tetracycline (TET), erythromycin (ERY), and chloramphenicol (CHL) as antibiotics. We detected the strongest synergies with 4NQO, an agent that oxidizes guanines and ultimately results in double-strand breaks when paired with the bactericidal antibiotics VAN, TMP, CPR, and GEN, but no synergies with the bacteriostatic antibiotics TET, ERY, and CHL. Each of the other mutagens displays synergies with the bactericidal antibiotics to various degrees that reflect their potencies, as well as with some of the other mutagens. The results support recent models showing that bactericidal antibiotics kill bacteria principally by ultimately generating more double-strand breaks than can be repaired. We discuss the synergies seen here and elsewhere as representing dose effects of not the proximal target damage but rather the ultimate resulting double-strand breaks. We also used the results of pairwise tests to place the classic mutagens into functional antibacterial categories within a previously defined drug interaction network. PMID:26711761

  7. Genotoxicity risk assessment of diversely substituted quinolines using the SOS chromotest.

    PubMed

    Duran, Leidy Tatiana Díaz; Rincón, Nathalia Olivar; Galvis, Carlos Eduardo Puerto; Kouznetsov, Vladimir V; Lorenzo, Jorge Luis Fuentes

    2015-03-01

    Quinolines are aromatic nitrogen compounds with wide therapeutic potential to treat parasitic and microbial diseases. In this study, the genotoxicity of quinoline, 4-methylquinoline, 4-nitroquinoline-1-oxide (4-NQO), and diversely functionalized quinoline derivatives and the influence of the substituents (functional groups and/or atoms) on their genotoxicity were tested using the SOS chromotest. Quinoline derivatives that induce genotoxicity by the formation of an enamine epoxide structure did not induce the SOS response in Escherichia coli PQ37 cells, with the exception of 4-methylquinoline that was weakly genotoxic. The chemical nature of the substitution (C-5 to C-8: hydroxyl, nitro, methyl, isopropyl, chlorine, fluorine, and iodine atoms; C-2: phenyl and 3,4-methylenedioxyphenyl rings) of quinoline skeleton did not significantly modify compound genotoxicities; however, C-2 substitution with α-, β-, or γ-pyridinyl groups removed 4-methylquinoline genotoxicity. On the other hand, 4-NQO derivatives whose genotoxic mechanism involves reduction of the C-4 nitro group were strong inducers of the SOS response. Methyl and nitrophenyl substituents at C-2 of 4-NQO core affected the genotoxic potency of this molecule. The relevance of these results is discussed in relation to the potential use of the substituted quinolines. The work showed the sensitivity of SOS chromotest for studying structure-genotoxicity relationships and bioassay-guided quinoline synthesis.

  8. Modulatory role of alizarin from Rubia cordifolia L. against genotoxicity of mutagens.

    PubMed

    Kaur, Prabhjit; Chandel, Madhu; Kumar, Subodh; Kumar, Neeraj; Singh, Bikram; Kaur, Satwinderjeet

    2010-01-01

    Rubia cordifolia L. (Rubiaceae) is an important medicinal plant used in the Ayurvedic medicinal system. Its use as a traditional therapeutic has been related to the treatment of skin disorders and cancer. Besides its medicinal value, anthraquinones from this plant are used as natural food colourants and as natural hair dyes. Dyes derived from natural sources have emerged as important alternatives to synthetic dyes. Alizarin (1,2-dihydroxyanthraquinone) was isolated and characterized from R. cordifolia L. and evaluated for its antigenotoxic potential against a battery of mutagens viz. 4-nitro-o-phenylenediamine (NPD) and 2-aminofluorene (2-AF) in Ames assay using TA98 tester strain of Salmonella typhimurium; hydrogen peroxide (H(2)O(2)) and 4-nitroquinoline-1-oxide (4NQO) in SOS chromotest using PQ37 strain of Escherichia coli and in Comet assay using human blood lymphocytes. Our results showed that alizarin possessed significant modulatory role against the genotoxicity of mutagens. PMID:19852997

  9. Loss of DNA repair capacity during successive subcultures of primary rat fibroblasts

    PubMed Central

    1977-01-01

    Cultures of fibroblasts from newborn rats and successive subcultures of these cells were treated with 4-nitroquinoline-1-oxide to induce DNA repair. DNA from the cultures was examined by velocity sedimentation in alkaline sucrose gradients immediately after drug treatment and after a post-treatment incubation period of 3 h. Early passage cells were able to repair the damage that appeared as single strand breaks, however, by the seventh subculture this activity was not apparent. Measurements of repair synthesis showed a partial loss of this capacity with successive subculture. The results fit a model in which 4NQO causes two kinds of DNA modification, one of which is alkali labile and appears as a single- strand break. Both modifications are subject to excision repair, but each is recognized initially by a specific endonuclease. In the late passage cells, the endonuclease specific for the alkali labile modification is absent. PMID:407232

  10. Peroxiredoxin 1 has an anti-apoptotic role via apoptosis signal-regulating kinase 1 and p38 activation in mouse models with oral precancerous lesions

    PubMed Central

    ZHANG, JIANFEI; JING, XINYING; NIU, WENWEN; ZHANG, MIN; GE, LIHUA; MIAO, CONGCONG; TANG, XIAOFEI

    2016-01-01

    Peroxiredoxin 1 (Prx1) is important in the protection of cells from oxidative damage and the regulation of cell proliferation and apoptosis. Prx1 is overexpressed in oral precancerous lesions of oral leukoplakia (OLK) and oral cancer; however, the association between Prx1 expression and OLK pathogenesis remains unknown. The present study investigated the role of Prx1 and its molecular mechanisms in oxidative stress-induced apoptosis during the pathogenesis of OLK. Wild-type and Prx1 knockout mice were treated with 50 µg/ml 4-nitroquinoline-1-oxide (4NQO) or 4NQO + H2O2 for 16 weeks to establish mouse models with tongue precancerous lesions. Apoptotic cells were detected using terminal deoxynucleotidyl transferase dUTP nick-end labeling assay. The expression of Prx1, apoptosis signal-regulating kinase 1 (ASK1), phosphor-ASK1, p38 and phosphor-p38 was analyzed using immunohistochemical staining, and their mRNA expression levels were evaluated by reverse transcription quantitative polymerase chain reaction. The present results demonstrated that 4NQO or 4NQO + H2O2 induced the development of tongue precancerous lesions in Prx1 knockout and wild-type mice. Prx1 was overexpressed in tongue precancerous lesions compared with normal tongue mucosa. There was a significant decrease in the degree of moderate or severe epithelial dysplasia, and mild epithelial dysplasia was clearly elevated, in Prx1 knockout mice treated with 4NQO + H2O2 compared with wild-type mice treated with 4NQO + H2O2. Prx1 suppressed apoptosis and upregulated phosphor-ASK1 and phosphor-p38 expression in tongue precancerous lesions. The present results suggest that Prx1 suppresses oxidative stress-induced apoptosis via the ASK1/p38 signalling pathway in mouse tongue precancerous lesions. In conclusion, Prx1 and H2O2 have a coordination role in promoting the progression of tongue precancerous mucosa lesions. The present findings provide novel insight into Prx1 function and the mechanisms of Prx1 in OLK

  11. Modulation of IL-1β reprogrammes the tumor microenvironment to interrupt oral carcinogenesis

    PubMed Central

    Wu, Tong; Hong, Yun; Jia, Lihua; Wu, Jie; Xia, Juan; Wang, Juan; Hu, Qinchao; Cheng, Bin

    2016-01-01

    Head and neck squamous cell carcinoma (HNSCC) development is a multistage process includes the normal, dysplasia and squamous cell carcinoma (SCC) stages. Recently, increasing evidence has suggested that the tumor microenvironment (TME) is an integral part of malignant transformation. Exploring certain key node genes in TME for future intervention in dysplasia to interrupt oral carcinogenesis was the primary goal of this research. To achieve this goal, systems biology approaches were first applied to the epithelia and fibroblasts collected at sequential stages in a 4-nitroquinoline-1-oxide (4NQO) - induced rat oral carcinogenesis model. Through bioinformatics network construction, IL-1β was identified as one of the key node genes in TME during carcinogenesis. Immunohistochemical staining of human and rat samples demonstrated that IL-1β expression patterns were parallel to the stages of malignant transformation. Silencing IL-1β with lentivirus-delivered shRNA significantly inhibited oral squamous cell carcinoma cell growth both in vivo and in vitro. Based on these findings, we hypothesized that IL-1β may be a chemoprevention target in TME during oral carcinogenesis. Therefore, we targeted IL-1 in the TME by oral mucosal injection of an IL-1 receptor antagonist in 4NQO rats. The results demonstrated that targeting IL-1 could interrupt oral carcinogenesis by reprogramming the TME. PMID:26831400

  12. Effects of chemical agent injections on genotoxicity of wastewater in a microfiltration-reverse osmosis membrane process for wastewater reuse.

    PubMed

    Tang, Fang; Hu, Hong-Ying; Wu, Qian-Yuan; Tang, Xin; Sun, Ying-Xue; Shi, Xiao-Lei; Huang, Jing-Jing

    2013-09-15

    With combined microfiltration (MF)/ultrafiltration (UF) and reverse osmosis (RO) process being widely used in municipal wastewater reclamation, RO concentrate with high level genotoxicity is becoming a potential risk to water environment. In this study, wastewater genotoxicity in a MF-RO process for municipal wastewater reclamation and also the effects of chemical agent injections were evaluated by SOS/umu genotoxicity test. The genotoxicity of RO concentrate ranged 500-559 μg 4-NQO (4-nitroquinoline-1-oxide)/L and 12-22 μg 4-NQO/mg DOC, was much higher than that of RO influent. Further research suggested that Kathon biocide was a key chemical agent associated with the genotoxicity increase. Kathon biocide used in RO system was highly genotoxic in vitro and Kathon biocide retained in RO system could contribute to a higher genotoxicity of RO concentrate. Hence, treatments for biocides before discharging are necessary. Chlorination of secondary effluent could significantly decrease the genotoxicity and increasing chlorine dosage could be an efficacious method to decrease the genotoxicity of RO concentrate. According to the result of the experiment, the dosage of chlorine in dual-membrane process could be set to about 2.5 mg Cl₂/L. The effect of antiscalant (2-phosphomobutane-1,2,4-tricarboxylic acid) was also investigated; it turned out to have no effect on genotoxicity.

  13. p53 Haploinsufficiency Profoundly Accelerates the Onset of Tongue Tumors in Mice Lacking the Xeroderma Pigmentosum Group A Gene

    PubMed Central

    Ide, Fumio; Kitada, Munenori; Sakashita, Hideaki; Kusama, Kaoru; Tanaka, Kiyoji; Ishikawa, Takatoshi

    2003-01-01

    Mice lacking the xeroderma pigmentosum group A gene (XPA−/− mice), which have a complete deficiency in nucleotide excision repair (NER), are highly predisposed to tongue squamous cell carcinoma (SCC) when exposed to 4-nitroquinoline 1-oxide (4NQO). To explore the effects of the interaction of the NER machinery with p53 in oral tumorigenesis, we generated an XPA−/− mouse strain carrying mutant alleles for p53. This mouse model of 4NQO carcinogenesis demonstrated that despite the same tumor frequency, XPA−/−p53+/− mice reached 100% SCC incidence at 25 weeks compared with 50 weeks for XPA−/−p53+/+ littermates. XPA−/−p53−/− mice succumbed to spontaneous thymic lymphomas before the development of tongue tumors (before 13 weeks of age). SCC originated in XPA−/−p53+/− mice maintained the p53+/− genotype and the retained wild-type p53 allele appeared to be structurally intact. Only one of 20 XPA−/−p53+/+ SCC showed a missense mutation of p53. Collectively, the accelerated tongue tumor growth may be a consequence of haploinsufficiency but not of mutation of p53 in the context of NER deficiency. PMID:14578172

  14. Methylation-Associated Gene Silencing of RARB in Areca Carcinogens Induced Mouse Oral Squamous Cell Carcinoma

    PubMed Central

    Tsou, Yung-An; Fan, Shin-Ru; Tsai, Ming-Hsui; Chen, Hsiao-Ling; Chang, Nai-Wen; Cheng, Ju-Chien

    2014-01-01

    Regarding oral squamous cell carcinoma (OSCC) development, chewing areca is known to be a strong risk factor in many Asian cultures. Therefore, we established an OSCC induced mouse model by 4-nitroquinoline-1-oxide (4-NQO), or arecoline, or both treatments, respectively. These are the main two components of the areca nut that could increase the occurrence of OSCC. We examined the effects with the noncommercial MCGI (mouse CpG islands) microarray for genome-wide screening the DNA methylation aberrant in induced OSCC mice. The microarray results showed 34 hypermethylated genes in 4-NQO plus arecoline induced OSCC mice tongue tissues. The examinations also used methylation-specific polymerase chain reaction (MS-PCR) and bisulfite sequencing to realize the methylation pattern in collected mouse tongue tissues and human OSCC cell lines of different grades, respectively. These results showed that retinoic acid receptor β (RARB) was indicated in hypermethylation at the promoter region and the loss of expression during cancer development. According to the results of real-time PCR, it was shown that de novo DNA methyltransferases were involved in gene epigenetic alternations of OSCC. Collectively, our results showed that RARB hypermethylation was involved in the areca-associated oral carcinogenesis. PMID:25197641

  15. The influence of organic solvents on estimates of genotoxicity and antigenotoxicity in the SOS chromotest

    PubMed Central

    Quintero, Nathalia; Stashenko, Elena E.; Fuentes, Jorge Luis

    2012-01-01

    In this work, the toxicity and genotoxicity of organic solvents (acetone, carbon tetrachloride, dichloromethane, dimethylsulfoxide, ethanol, ether and methanol) were studied using the SOS chromotest. The influence of these solvents on the direct genotoxicity induced by the mutagens mitomycin C (MMC) and 4-nitroquinoline-1-oxide (4-NQO) were also investigated. None of the solvents were genotoxic in Escherichia coli PQ37. However, based on the inhibition of protein synthesis assessed by constitutive alkaline phosphatase activity, some solvents (carbon tetrachloride, dimethylsulfoxide, ethanol and ether) were toxic and incompatible with the SOS chromotest. Solvents that were neither toxic nor genotoxic to E. coli (acetone, dichloromethane and methanol) significantly reduced the genotoxicity of MMC and 4-NQO. When these solvents were used to dissolve vitamin E they increased the antigenotoxic activity of this compound, possibly through additive or synergistic effects. The relevance of these results is discussed in relation to antigenotoxic studies. These data indicate the need for careful selection of an appropriate diluent for the SOS chromotest since some solvents can modulate genotoxicity and antigenotoxicity. PMID:22888301

  16. Efficacy of quercetin against chemically induced murine oral squamous cell carcinoma

    PubMed Central

    DROGUETT, DANIEL; CASTILLO, CHRISTIAN; LEIVA, ELBA; THEODULOZ, CRISTINA; SCHMEDA-HIRSCHMANN, GUILLERMO; KEMMERLING, ULRIKE

    2015-01-01

    Oral squamous cell carcinoma (OSCC) is the most common form of head and neck cancer, and oxidative damage is associated with the development of OSCCs. Antioxidants have therefore been proposed for use as chemoprotective agents against different types of cancer. In the present study, the effect of the antioxidant quercetin, administered at doses of 10 and 100 mg/kg/day, was investigated in an experimental murine model of 4-nitroquinoline 1-oxide (4-NQO)-induced carcinogenesis. The survival of the treated animals, the plasmatic levels of reduced glutathione and the type and severity of lesions (according the International Histological Classification of Tumors and Bryne's Multifactorial Grading System for the Invasive Tumor Front) were assessed. Additionally, the organization of the extracellular matrix was analyzed by carbohydrate and collagen histochemistry, and immunohistochemistry was used to assess the expression of the tumor markers proliferating cell nuclear antigen and mutated p53. The results indicate that, despite the promising effect of quercetin in other studies, this drug is ineffective as a chemoprotective agent against 4-NQO-induced OSCC in mice at the assayed doses. PMID:26622865

  17. Genotoxicity is modulated by ascorbic acid. Studies using the wing spot test in Drosophila.

    PubMed

    Kaya, Bülent; Creus, Amadeu; Velázquez, Antonia; Yanikoğlu, Atila; Marcos, Ricardo

    2002-09-26

    The ability of ascorbic acid (Vitamin C) to modulate the genotoxic action of several mutagens was investigated in the wing spot test of Drosophila melanogaster. In this assay, 3-day-old transheterozygous larvae for the multiple wing hairs (mwh, 3-0.3) and flare (flr, 3-38.8) genes were treated with three reference mutagenic compounds, namely cobalt chloride (CoCl2), 4-nitroquinoline 1-oxide (4-NQO) and potassium dichromate (K2Cr2O7). The results obtained show that the three reference mutagens tested were clearly genotoxic in the Drosophila wing somatic mutation and recombination test (SMART). None of the three concentrations tested of ascorbic acid (25, 75 and 250mM) induced significant increases in the frequency of the mutant clones recorded. When co-treatment experiments with ascorbic acid were carried out, different results were found. Thus, ascorbic acid was effective in reducing the genotoxicity of K2Cr2O7 virtually to the control level; on the contrary, it did not show any antigenotoxic effect on the genotoxicity of 4-NQO. Finally, co-treatments with CoCl2 and ascorbic acid show a significant increase in the frequency of mutant clones over the values obtained with CoCl2 alone. PMID:12297148

  18. DNA damage induction of ribonucleotide reductase.

    PubMed

    Elledge, S J; Davis, R W

    1989-11-01

    RNR2 encodes the small subunit of ribonucleotide reductase, the enzyme that catalyzes the first step in the pathway for the production of deoxyribonucleotides needed for DNA synthesis. RNR2 is a member of a group of genes whose activities are cell cycle regulated and that are transcriptionally induced in response to the stress of DNA damage. An RNR2-lacZ fusion was used to further characterize the regulation of RNR2 and the pathway responsible for its response to DNA damage. beta-Galactosidase activity in yeast strains containing the RNR2-lacZ fusion was inducible in response to DNA-damaging agents (UV light, 4-nitroquinoline-1-oxide [4-NQO], and methyl methanesulfonate [MMS]) and agents that block DNA replication (hydroxyurea [HU] and methotrexate) but not heat shock. When MATa cells were arrested in G1 by alpha-factor, RNR2 mRNA was still inducible by DNA damage, indicating that the observed induction can occur outside of S phase. In addition, RNR2 induction was not blocked by the presence of cycloheximide and is therefore likely to be independent of protein synthesis. A mutation, rnr2-314, was found to confer hypersensitivity to HU and increased sensitivity to MMS. In rnr2-314 mutant strains, the DNA damage stress response was found to be partially constitutive as well as hypersensitive to induction by HU but not MMS. The induction properties of RNR2 were examined in a rad4-2 mutant background; in this genetic background, RNR2 was hypersensitive to induction by 4-NQO but not MMS. Induction of the RNR2-lacZ fusion in a RAD(+) strain in response to 4-NQO was not enhanced by the presence of an equal number of rad4-2 cells that lacked the fusion, implying that the DNA damage stress response in cell autonomous. PMID:2513480

  19. The ATPase domain but not the acidic region of Cockayne syndrome group B gene product is essential for DNA repair.

    PubMed

    Brosh, R M; Balajee, A S; Selzer, R R; Sunesen, M; Proietti De Santis, L; Bohr, V A

    1999-11-01

    Cockayne syndrome (CS) is a human genetic disorder characterized by UV sensitivity, developmental abnormalities, and premature aging. Two of the genes involved, CSA and CSB, are required for transcription-coupled repair (TCR), a subpathway of nucleotide excision repair that removes certain lesions rapidly and efficiently from the transcribed strand of active genes. CS proteins have also been implicated in the recovery of transcription after certain types of DNA damage such as those lesions induced by UV light. In this study, site-directed mutations have been introduced to the human CSB gene to investigate the functional significance of the conserved ATPase domain and of a highly acidic region of the protein. The CSB mutant alleles were tested for genetic complementation of UV-sensitive phenotypes in the human CS-B homologue of hamster UV61. In addition, the CSB mutant alleles were tested for their ability to complement the sensitivity of UV61 cells to the carcinogen 4-nitroquinoline-1-oxide (4-NQO), which introduces bulky DNA adducts repaired by global genome repair. Point mutation of a highly conserved glutamic acid residue in ATPase motif II abolished the ability of CSB protein to complement the UV-sensitive phenotypes of survival, RNA synthesis recovery, and gene-specific repair. These data indicate that the integrity of the ATPase domain is critical for CSB function in vivo. Likewise, the CSB ATPase point mutant failed to confer cellular resistance to 4-NQO, suggesting that ATP hydrolysis is required for CSB function in a TCR-independent pathway. On the contrary, a large deletion of the acidic region of CSB protein did not impair the genetic function in the processing of either UV- or 4-NQO-induced DNA damage. Thus the acidic region of CSB is likely to be dispensable for DNA repair, whereas the ATPase domain is essential for CSB function in both TCR-dependent and -independent pathways. PMID:10564257

  20. Ethanol Promotes Chemically Induced Oral Cancer in Mice through Activation of the 5-Lipoxygenase Pathway of Arachidonic Acid Metabolism

    PubMed Central

    Guo, Yizhu; Wang, Xin; Zhang, Xinyan; Sun, Zheng; Chen, Xiaoxin

    2011-01-01

    Alcohol drinking is a known risk factor for oral cancer in humans. However, previous animal studies on the promoting effect of ethanol on oral carcinogenesis were inconclusive. It is necessary to develop an animal model with which the molecular mechanism of ethanol-related oral carcinogenesis may be elucidated in order to develop effective prevention strategies. In this study, mice were first treated with 4-nitroquinoline-1-oxide (4NQO, 100μg/ml in drinking water) for 8 weeks, and then given water or ethanol (8%) as the sole drink for another 16 weeks. During the experiment, 8% ethanol was well tolerated by mice. The incidence of squamous cell carcinoma (SCC) increased from 20% (8/41) to 43% (17/40; p<0.05). Expression of 5-lipoxygenase (5-Lox) and cyclooxygenase 2 (Cox-2) was increased in dysplasia and SCC of 4NQO-treated tongues, and further enhanced by ethanol. Using this mouse model, we further demonstrated that fewer cancers were induced in Alox5−/− mice, as were cell proliferation, inflammation, and angiogenesis in the tongue, as compared with Alox5+/+ mice. Interestingly, Cox-2 expression was induced by ethanol in knockout mice, while 5-Lox and leukotriene A4 hydrolase (LTA4H) expression and leukotriene B4 (LTB4) biosynthesis were dramatically reduced. Moreover, ethanol enhanced expression and nuclear localization of 5-Lox and stimulated LTB4 biosynthesis in human tongue SCC cells (SCC-15 and SCC-4) in vitro. In conclusion, this study clearly demonstrated that ethanol promoted 4NQO-induced oral carcinogenesis, at least in part, through further activation of the 5-Lox pathway of arachidonic acid metabolism. PMID:21881027

  1. [Photochemical reactivity of methaqualone-1-oxide].

    PubMed

    Theil, F P; Pöhlmann, H; Pfeifer, S; Franke, P

    1985-05-01

    The photoreactivity of methaqualone-1-oxide a main metabolite of the hypnotic methaqualone has been studied in polar and apolar solvents using UV- and daylight. Five photoproducts were isolated and identified by their analytical behaviour (TLC, UV, IR, high-resolution MS). The structure of the compounds 4, 6, 7, and 8 refer to unstable, reactive intermediates (oxaziridine, biradical) during the photolysis.

  2. Phenotypic consequences of mutations in the conserved motifs of the putative helicase domain of the human Cockayne syndrome group B gene.

    PubMed

    Muftuoglu, Meltem; Selzer, Rebecca; Tuo, Jingsheng; Brosh, Robert M; Bohr, Vilhelm A

    2002-01-23

    Cockayne syndrome (CS) is a human genetic disorder characterized by several neurological and developmental abnormalities. Two genetic complementation groups, CS-A and CS-B, have been identified. The CSB protein belongs to helicase superfamily 2, and to the SWI/SNF family of proteins. The CSB protein is implicated in transcription-coupled repair (TCR), basal transcription and chromatin remodeling. In addition, CS cells undergo UV-induced apoptosis at much lower doses than normal cells. However, the molecular function of the CSB protein in these biological pathways has remained unclear. Evidence indicates that the integrity of the Walker A and B boxes (motifs I and II) are important for CSB function, but the functional significance of the helicase motifs Ia, III--IV has not been previously examined. In this study, single amino acid changes in highly conserved residues of helicase motifs Ia, III, V, VI and a second putative nucleotide-binding motif (NTB) of the CSB protein were generated by site-directed mutagenesis to analyze the genetic function of the CSB protein in survival, RNA synthesis recovery and apoptosis after UV treatment. The survival analysis of these CS-B mutant cell lines was also performed after treatment with the chemical carcinogen, 4-nitroquinoline-1-oxide (4-NQO). The lesions induced by UV light, cyclobutane pyrimidine dimers, are known to be repaired by TCR whereas the lesions induced by 4-NQO are repaired by global genome repair. The results of this study demonstrate that the point mutations in highly conserved residues of helicase motifs Ia, III, V and VI abolished the genetic function of the CSB protein in survival, RNA synthesis recovery and apoptosis after UV treatment. Similarly, the same mutants failed to complement the sensitivity toward 4-NQO. Thus, the integrity of these helicase motifs is important for the biological function of the CSB protein. On the contrary, a point mutation in a C-terminal, second, NTB motif of the CSB protein

  3. Chemopreventive effect of a xanthine oxidase inhibitor, 1'-acetoxychavicol acetate, on rat oral carcinogenesis.

    PubMed

    Ohnishi, M; Tanaka, T; Makita, H; Kawamori, T; Mori, H; Satoh, K; Hara, A; Murakami, A; Ohigashi, H; Koshimizu, K

    1996-04-01

    The effect of a xanthine oxidase inhibitor, 1'-acetoxychavicol acetate (ACA), on 4-nitroquinoline 1-oxide (4-NQO)-induced oral carcinogenesis was investigated in male F344 rats. All rats except those in the ACA-alone and untreated groups were given 4-NQO (20 ppm) In the drinking water for 8 weeks to induce oral cancer. Starting 1 week before the 4-NQO exposure, animals were fed diet containing 100 ppm or 500 ppm ACA for 10 weeks, followed by the basal diet without ACA for 22 weeks. Other groups were fed the diet containing ACA at 100 ppm or 500 ppm for 22 weeks, starting 1 week after the cessation of 4-NQO exposure. The remaining groups consisted of rats given 500 ppm ACA alone or untreated rats. At the termination of the experiment (32 weeks), the incidences of tongue neoplasms and preneoplastic lesions, polyamine levels in the tongue tissue, and cell proliferation activity estimated in terms of 5-bromodeoxyuridine (BrdU)-labeling index and by morphometric analysis of silver-stained nucleolar organizer regions' protein (AgNORs) were compared among the groups. Feeding of ACA at the two doses during initiation or postinitiation significantly decreased the development of tongue carcinoma (93-100% reduction, P < 0.001) and preneoplasia (43-50% reduction for hyperplasia and 34-48% reduction for dysplasia, P < 0.05). There were no such lesions in rats fed ACA alone or those in the untreated control group. The number of AgNORs per cell nucleus was significantly decreased by feeding of ACA at a high dose (500 ppm) (29% inhibition, P < 0.05). The BrdU-labeling index was also reduced by dietary administration of ACA (23-32% inhibition, P < 0.01). In addition, ACA feeding reduced tongue polyamine levels (35-40% inhibition, P < 0.05). These results indicate that ACA inhibited rat oral carcinogenesis, and such inhibition might be related to suppression of cell proliferation in the oral mucosa by the xanthine oxidase inhibitor.

  4. Evaluation of the Effect of Two Different Systemic Doses of Viola Odorata on Prevention of Induced Tongue Dysplasia in Rats

    PubMed Central

    Helli, Sanaz; Damghani, Hossein; Mohajeri, Daryoush; Mesgari Abbasi, Mehran; Attaran, Rana; Zahed, Maryam

    2016-01-01

    Statement of the Problem Oral cancer is among the ten most common cancers worldwide. It affects the life quality of patients in many ways. Purpose The aim of this study was to compare the effects of two different systemic doses of Viola Odorata syrup on the prevention of 4-Nitroquinoline-1-oxide (4-NQO) induced tongue dysplasia in rats. Materials and Method Forty-eight male Wistar rats were divided into four groups of A, B, C and D. Group A served as the control group. The rats in groups B to D received 30 ppm of 4-NQO in drinking water for 12 weeks. Additionally, the rats in groups B and C received Viola Odorata syrup at doses of 15 and 5 ml/kg, respectively, 3 times a week. Body weights were measured three times a week. At the end, the rats were euthanized and the tongue was removed. Histological evaluations for carcinogenesis were carried out under a light microscope. Results The mean body weight of the rats in groups B, C, and D were lower than that in group A (p< 0.01). After 12 weeks of treatment, microscopically no histological changes of the tongue base epithelia were observed in the control group. The rats in group B did not show severe dysplastic changes; only mild to moderate histological changes including hyperplasia and hyperkeratosis were evident. These incidences were significantly more apparent in groups C with moderate to severe changes (p< 0.05) and group D with severe dysplastic changes (p< 0.01). Almost all rats in group D had hyperplasia and manifested all of the stages of dysplasia. Conclusion Viola Odorata extract has dose-dependent inhibitory effects on the development of tongue induced dysplasia. PMID:27602393

  5. Novel ß-HPV49 Transgenic Mouse Model of Upper Digestive Tract Cancer.

    PubMed

    Viarisio, Daniele; Müller-Decker, Karin; Zanna, Paola; Kloz, Ulrich; Aengeneyndt, Birgit; Accardi, Rosita; Flechtenmacher, Christa; Gissmann, Lutz; Tommasino, Massimo

    2016-07-15

    The beta genus of human papillomaviruses (ß-HPV) includes approximately 50 different viral types that are subdivided into five species (ß-1 through ß-5). Nonmelanoma cancers may involve some ß-1 and ß-2 HPV types, but the biology of most ß-HPV types and their possible connections to human disease are still little characterized. In this study, we studied the effects of ß-3 type HPV49 in a novel transgenic (Tg) mouse model, using a cytokeratin K14 promoter to drive expression of the E6 and E7 genes from this virus in the basal skin epidermis and the mucosal epithelia of the digestive tract (K14 HPV49 E6/E7-Tg mice). Viral oncogene expression only marginally increased cellular proliferation in the epidermis of Tg animals, compared with wild-type littermates, and we observed no spontaneous tumor formation during their entire lifespan. However, we found that K14 HPV49 E6/E7-Tg mice were highly susceptible to upper digestive tract carcinogenesis upon initiation with 4-nitroquinoline 1-oxide (4NQO). This was a selective effect, as the same mice did not exhibit any skin lesions after chronic UV irradiation. Opposite results were observed in an analogous Tg model expressing the ß-2 HPV38 E6 and E7 oncogenes at the same anatomic sites. While these mice were highly susceptible to UV-induced skin carcinogenesis, as previously shown, they were little affected by 4NQO treatment. Overall, our findings highlight important differences in the biologic properties of certain ß-type HPV that affect their impact on carcinogenesis in an anatomic site-specific manner. Cancer Res; 76(14); 4216-25. ©2016 AACR.

  6. Assessment of the mutagenic potential of Cr(VI) in the oral mucosa of Big Blue® transgenic F344 rats.

    PubMed

    Thompson, Chad M; Young, Robert R; Suh, Mina; Dinesdurage, Harshini R; Elbekai, Reem H; Harris, Mark A; Rohr, Annette C; Proctor, Deborah M

    2015-08-01

    Exposure to high concentrations of hexavalent chromium [Cr(VI)] in drinking water was associated with an increased incidence of oral tumors in F344 rats in a 2-year cancer bioassay conducted by the National Toxicology Program. These tumors primarily occurred at 180 ppm Cr(VI) and appeared to originate from the gingival mucosa surrounding the upper molar teeth. To investigate whether these tumors could have resulted from a mutagenic mode of action (MOA), a transgenic mutation assay based on OECD Test Guideline 488 was conducted in Big Blue(®) TgF344 rats. The mutagenic oral carcinogen 4-nitroquinoline-1-oxide (4-NQO) served as a positive control. Mutant frequency was measured in the inner gingiva with adjacent palate, and outer gingiva with adjacent buccal tissue. Exposure to 10 ppm 4-NQO in drinking water for 28 days increased mutant frequency in the cII transgene significantly, from 39.1 ± 7.5 × 10(-6) to 688 ± 250 × 10(-6) in the gingival/buccal region, and from 49.8 ± 17.8 × 10(-6) to 1818 ± 362 × 10(-6) in the gingival/palate region. Exposure to 180 ppm Cr(VI) in drinking water for 28 days did not significantly increase the mutant frequency in the gingival/buccal (44.4 ± 25.4 × 10(-6)) or the gingival/palate (57.8 ± 9.1 × 10(-6)) regions relative to controls. These data indicate that high (∼180,000 times expected human exposure), tumorigenic concentrations of Cr(VI) did not significantly increase mutations in the gingival epithelium, and suggest that Cr(VI) does not act by a mutagenic MOA in the rat oral cavity. PMID:26010270

  7. Assessment of the mutagenic potential of Cr(VI) in the oral mucosa of Big Blue® transgenic F344 rats.

    PubMed

    Thompson, Chad M; Young, Robert R; Suh, Mina; Dinesdurage, Harshini R; Elbekai, Reem H; Harris, Mark A; Rohr, Annette C; Proctor, Deborah M

    2015-08-01

    Exposure to high concentrations of hexavalent chromium [Cr(VI)] in drinking water was associated with an increased incidence of oral tumors in F344 rats in a 2-year cancer bioassay conducted by the National Toxicology Program. These tumors primarily occurred at 180 ppm Cr(VI) and appeared to originate from the gingival mucosa surrounding the upper molar teeth. To investigate whether these tumors could have resulted from a mutagenic mode of action (MOA), a transgenic mutation assay based on OECD Test Guideline 488 was conducted in Big Blue(®) TgF344 rats. The mutagenic oral carcinogen 4-nitroquinoline-1-oxide (4-NQO) served as a positive control. Mutant frequency was measured in the inner gingiva with adjacent palate, and outer gingiva with adjacent buccal tissue. Exposure to 10 ppm 4-NQO in drinking water for 28 days increased mutant frequency in the cII transgene significantly, from 39.1 ± 7.5 × 10(-6) to 688 ± 250 × 10(-6) in the gingival/buccal region, and from 49.8 ± 17.8 × 10(-6) to 1818 ± 362 × 10(-6) in the gingival/palate region. Exposure to 180 ppm Cr(VI) in drinking water for 28 days did not significantly increase the mutant frequency in the gingival/buccal (44.4 ± 25.4 × 10(-6)) or the gingival/palate (57.8 ± 9.1 × 10(-6)) regions relative to controls. These data indicate that high (∼180,000 times expected human exposure), tumorigenic concentrations of Cr(VI) did not significantly increase mutations in the gingival epithelium, and suggest that Cr(VI) does not act by a mutagenic MOA in the rat oral cavity.

  8. Impact of Short-term 1,25-Dihydroxyvitamin D3 on the Chemopreventive Efficacy of Erlotinib against Oral Cancer.

    PubMed

    Bothwell, Katelyn D; Shaurova, Tatiana; Merzianu, Mihai; Suresh, Amritha; Kuriakose, Moni A; Johnson, Candace S; Hershberger, Pamela A; Seshadri, Mukund

    2015-09-01

    Activation of the epidermal growth factor receptor (EGFR) pathway is an early event in head and neck carcinogenesis. As a result, targeting EGFR for chemoprevention of head and neck squamous cell carcinomas (HNSCC) has received considerable attention. In the present study, we examined the impact of 1,25(OH)2D3, the active metabolite of the nutritional supplement vitamin D on the chemopreventive efficacy of the EGFR inhibitor, erlotinib, against HNSCC. Experimental studies were conducted in patient-derived xenografts (PDX) and the 4-nitroquinoline-1-oxide (4NQO) carcinogen-induced model of HNSCC. Short-term treatment (4 weeks) of PDX-bearing mice with 1,25(OH)2D3 and erlotinib resulted in significant inhibition of tumor growth. Noninvasive MRI enabled longitudinal monitoring of disease progression in the 4NQO model with 100% of control animals showing evidence of neoplastic lesions by 24 weeks. Among the experimental groups, animals treated with the combination regimen showed the greatest reduction in tumor incidence and volume (P < 0.05). Combination treatment was well tolerated and was not associated with any significant change in body weight. Histopathologic assessment revealed a significant reduction in the degree of dysplasia with combination treatment. Immunoblot analysis of whole tongue extracts showed downregulation of phospho-EGFR and phospho-Akt with the combination regimen. These results highlight the potential of 1,25(OH)2D3 to augment the efficacy of erlotinib against HNSCC. Further optimization of schedule and sequence of this combination regimen along with investigation into the activity of less calcemic analogues or dietary vitamin D is essential to fully realize the potential of this approach.

  9. Evaluation of the Effect of Two Different Systemic Doses of Viola Odorata on Prevention of Induced Tongue Dysplasia in Rats

    PubMed Central

    Helli, Sanaz; Damghani, Hossein; Mohajeri, Daryoush; Mesgari Abbasi, Mehran; Attaran, Rana; Zahed, Maryam

    2016-01-01

    Statement of the Problem Oral cancer is among the ten most common cancers worldwide. It affects the life quality of patients in many ways. Purpose The aim of this study was to compare the effects of two different systemic doses of Viola Odorata syrup on the prevention of 4-Nitroquinoline-1-oxide (4-NQO) induced tongue dysplasia in rats. Materials and Method Forty-eight male Wistar rats were divided into four groups of A, B, C and D. Group A served as the control group. The rats in groups B to D received 30 ppm of 4-NQO in drinking water for 12 weeks. Additionally, the rats in groups B and C received Viola Odorata syrup at doses of 15 and 5 ml/kg, respectively, 3 times a week. Body weights were measured three times a week. At the end, the rats were euthanized and the tongue was removed. Histological evaluations for carcinogenesis were carried out under a light microscope. Results The mean body weight of the rats in groups B, C, and D were lower than that in group A (p< 0.01). After 12 weeks of treatment, microscopically no histological changes of the tongue base epithelia were observed in the control group. The rats in group B did not show severe dysplastic changes; only mild to moderate histological changes including hyperplasia and hyperkeratosis were evident. These incidences were significantly more apparent in groups C with moderate to severe changes (p< 0.05) and group D with severe dysplastic changes (p< 0.01). Almost all rats in group D had hyperplasia and manifested all of the stages of dysplasia. Conclusion Viola Odorata extract has dose-dependent inhibitory effects on the development of tongue induced dysplasia.

  10. Prevention of Carcinogen-Induced Oral Cancer by Sulforaphane.

    PubMed

    Bauman, Julie E; Zang, Yan; Sen, Malabika; Li, Changyou; Wang, Lin; Egner, Patricia A; Fahey, Jed W; Normolle, Daniel P; Grandis, Jennifer R; Kensler, Thomas W; Johnson, Daniel E

    2016-07-01

    Chronic exposure to carcinogens represents the major risk factor for head and neck squamous cell carcinoma (HNSCC). Beverages derived from broccoli sprout extracts (BSE) that are rich in glucoraphanin and its bioactive metabolite sulforaphane promote detoxication of airborne pollutants in humans. Herein, we investigated the potential chemopreventive activity of sulforaphane using in vitro models of normal and malignant mucosal epithelial cells and an in vivo model of murine oral cancer resulting from the carcinogen 4-nitroquinoline-1-oxide (4NQO). Sulforaphane treatment of Het-1A, a normal mucosal epithelial cell line, and 4 HNSCC cell lines led to dose- and time-dependent induction of NRF2 and the NRF2 target genes NQO1 and GCLC, known mediators of carcinogen detoxication. Sulforaphane also promoted NRF2-independent dephosphorylation/inactivation of pSTAT3, a key oncogenic factor in HNSCC. Compared with vehicle, sulforaphane significantly reduced the incidence and size of 4NQO-induced tongue tumors in mice. A pilot clinical trial in 10 healthy volunteers evaluated the bioavailability and pharmacodynamic activity of three different BSE regimens, based upon urinary sulforaphane metabolites and NQO1 transcripts in buccal scrapings, respectively. Ingestion of sulforaphane-rich BSE demonstrated the greatest, most consistent bioavailability. Mucosal bioactivity, defined as 2-fold or greater upregulation of NQO1 mRNA, was observed in 6 of 9 evaluable participants ingesting glucoraphanin-rich BSE; 3 of 6 ingesting sulforaphane-rich BSE; and 3 of 9 after topical-only exposure to sulforaphane-rich BSE. Together, our findings demonstrate preclinical chemopreventive activity of sulforaphane against carcinogen-induced oral cancer, and support further mechanistic and clinical investigation of sulforaphane as a chemopreventive agent against tobacco-related HNSCC. Cancer Prev Res; 9(7); 547-57. ©2016 AACR.

  11. Novel ß-HPV49 Transgenic Mouse Model of Upper Digestive Tract Cancer.

    PubMed

    Viarisio, Daniele; Müller-Decker, Karin; Zanna, Paola; Kloz, Ulrich; Aengeneyndt, Birgit; Accardi, Rosita; Flechtenmacher, Christa; Gissmann, Lutz; Tommasino, Massimo

    2016-07-15

    The beta genus of human papillomaviruses (ß-HPV) includes approximately 50 different viral types that are subdivided into five species (ß-1 through ß-5). Nonmelanoma cancers may involve some ß-1 and ß-2 HPV types, but the biology of most ß-HPV types and their possible connections to human disease are still little characterized. In this study, we studied the effects of ß-3 type HPV49 in a novel transgenic (Tg) mouse model, using a cytokeratin K14 promoter to drive expression of the E6 and E7 genes from this virus in the basal skin epidermis and the mucosal epithelia of the digestive tract (K14 HPV49 E6/E7-Tg mice). Viral oncogene expression only marginally increased cellular proliferation in the epidermis of Tg animals, compared with wild-type littermates, and we observed no spontaneous tumor formation during their entire lifespan. However, we found that K14 HPV49 E6/E7-Tg mice were highly susceptible to upper digestive tract carcinogenesis upon initiation with 4-nitroquinoline 1-oxide (4NQO). This was a selective effect, as the same mice did not exhibit any skin lesions after chronic UV irradiation. Opposite results were observed in an analogous Tg model expressing the ß-2 HPV38 E6 and E7 oncogenes at the same anatomic sites. While these mice were highly susceptible to UV-induced skin carcinogenesis, as previously shown, they were little affected by 4NQO treatment. Overall, our findings highlight important differences in the biologic properties of certain ß-type HPV that affect their impact on carcinogenesis in an anatomic site-specific manner. Cancer Res; 76(14); 4216-25. ©2016 AACR. PMID:27216183

  12. Inhibition of EGFR-STAT3 signaling with erlotinib prevents carcinogenesis in a chemically-induced mouse model of oral squamous cell carcinoma.

    PubMed

    Leeman-Neill, Rebecca J; Seethala, Raja R; Singh, Shivendra V; Freilino, Maria L; Bednash, Joseph S; Thomas, Sufi M; Panahandeh, Mary C; Gooding, William E; Joyce, Sonali C; Lingen, Mark W; Neill, Daniel B; Grandis, Jennifer R

    2011-02-01

    Chemoprevention of head and neck squamous cell carcinoma (HNSCC), a disease associated with high mortality rates and frequent occurrence of second primary tumor (SPT), is an important clinical goal. The epidermal growth factor receptor (EGFR)-signal transducer and activator of transcription (STAT)-3 signaling pathway is known to play a key role in HNSCC growth, survival, and prognosis, thereby serving as a potential therapeutic target in the treatment of HNSCC. In the current study, the 4-nitroquinoline-1-oxide (4-NQO)-induced murine model of oral carcinogenesis was utilized to investigate the chemopreventive activities of compounds that target the EGFR-STAT3 signaling pathway. This model mimics the process of oral carcinogenesis in humans. The drugs under investigation included erlotinib, a small molecule inhibitor of the EGFR, and guggulipid, the extract of an Ayurvedic medicinal plant, which contains guggulsterone, a compound known to inhibit STAT3. Dietary administration of guggulipid failed to confer protection against oral carcinogenesis. On the other hand, the mice placed on erlotinib-supplemented diet exhibited a 69% decrease (P < 0.001) in incidence of preneoplastic and neoplastic lesions compared with mice on the control diet. Immunostaining of dysplastic lesions demonstrated modest decreases in STAT3 levels, with both drug treatments, that were not statistically significant. The results of the present study provide the basis for exploring the efficacy of erlotinib for prevention of HNSCC in a clinical setting. PMID:21163936

  13. Relationship of DNA repair processes to mutagenesis and carcinogenesis in mammalian cells. Progress report, August 1, 1977-October 31, 1980

    SciTech Connect

    Evans, H.H.

    1980-10-01

    The objective of this research is to determine the role of DNA repair in mutagenesis and carcinogenesis in mammalian cells. More specifically, mutant strains will be selected which are deficient in various DNA repair pathways. These strains will be studied with regard to (1) the nature of the defect in repair, and (2) the mutability and transformability of the defective cells by various agents as compared to the wild type parental cells. The results to date include progress in the following areas: (1) determination of optimum conditions for growth and maintenance of cells and for quantitative measurement of various cellular parameters; (2) investigation of the effect of holding mutagenized cells for various periods in a density inhibited state on survival and on mutation and transformation frequencies; (3) examination of the repair capabilities of BHK cells, as compared to repair-proficient and repair-deficient human cells and excision-deficient mouse cells, as measured by the reactivation of Herpes simplex virus (HSV) treated with radiation and ethylmethane sulfonate (EMS); (4) initiation of host cell reactivation viral sucide enrichment and screening of survivors of the enrichment for sensitivity to ionizing radiation; and (5) investigation of the toxicity, mutagenicity, and carcinogenicity of various metabolites of 4-nitroquinoline-1-oxide (4-NQO). (ERB)

  14. Gene expression profiling signatures for the diagnosis and prevention of oral cavity carcinogenesis-genome-wide analysis using RNA-seq technology

    PubMed Central

    Tang, Xiao-Han; Zhang, Tuo; Scognamiglio, Theresa; Gudas, Lorraine J.

    2015-01-01

    We compared the changes in global gene expression between an early stage (the termination of the carcinogen treatment and prior to the appearance of frank tumors) and a late stage (frank squamous cell carcinoma (SCC)) of tongue carcinogenesis induced by the carcinogen 4-nitroquinoline 1-oxide (4-NQO) in a mouse model of human oral cavity and esophageal squamous cell carcinoma. Gene ontology and pathway analyses show that increases in “cell cycle progression” and “degradation of basement membrane and ECM pathways” are early events during SCC carcinogenesis and that changes in these pathways are even greater in the actual tumors. Myc, NFκB complex (NFKB1/RELA), and FOS transcription networks are the major transcriptional networks induced in early stage tongue carcinogenesis. Decreases in metabolism pathways, such as in “tricarboxylic acid cycle” and “oxidative phosphorylation”, occurred only in the squamous cell carcinomas and not in the early stages of carcinogenesis. We detected increases in ALDH1A3, PTGS2, and KRT1 transcripts in both the early and late stages of carcinogenesis. The identification of the transcripts and pathways that change at an early stage of carcinogenesis provides potentially useful information for early diagnosis and for prevention strategies for human tongue squamous cell carcinomas. PMID:26110572

  15. Limonin Methoxylation Influences Induction of Glutathione S-Transferase and Quinone Reductase

    PubMed Central

    PEREZ, JOSE LUIS; JAYAPRAKASHA, G. K.; VALDIVIA, VIOLETA; MUNOZ, DIANA; DANDEKAR, DEEPAK V.; AHMAD, HASSAN; PATIL, BHIMANAGOUDA S.

    2009-01-01

    Previous studies have indicated the chemoprevention potential of citrus limonoids due to the induction of phase II detoxifying enzymes. In the present study, three citrus limonoids were purified and identified from sour orange seeds as limonin, limonin glucoside (LG), deacetylnomilinic acid glucoside (DNAG). In addition, limonin was modified to defuran limonin and limonin 7-methoxime. The structures of these compounds were confirmed by NMR studies. These five compounds were used to investigate the influence of Phase II enzymes in female A/J mice. Our results indicated that the highest induction of Glutathione S-Transferase (GST) activity against 1-chloro-2, 4-dinitrobenzene (CDNB) by DNAG (67%) in lung homogenates followed by limonin-7-methoxime (32%) in treated liver homogenates. Interestingly, the limonin-7-methoxime showed the highest GST activity (270%) in liver against 4-nitroquinoline 1-oxide (4NQO), while the same compound in stomach induced GST by 51% compared to the control. DNAG treated group induced 55% in stomach homogenates. Another Phase II enzyme, quinone reductase (QR), was significantly induced by limonin-7-methoxime by 65 and 32% in liver and lung homogenates, respectively. Defuran limonin, induced QR in lung homogenates by 45%. Our results indicated that modification of the limonin have differential induction of phase II enzymes. These findings are indicative of a possible mechanism for the prevention of cancer by aiding in detoxification of xenobiotics. PMID:19480426

  16. Salmonella typhimurium mutagenicity tester strains that overexpress oxygen-insensitive nitroreductases nfsA and nfsB.

    PubMed

    Carroll, C C; Warnakulasuriyarachchi, D; Nokhbeh, M R; Lambert, I B

    2002-04-25

    We have designed and constructed a series of plasmids that contain the major and/or minor Escherichia coli nitroreductase genes, nfsA and nfsB, in different combinations with R plasmid mucA/B genes and the Salmonella typhimurium OAT gene. The plasmid encoded gene products are necessary for both the metabolic activation of a range of structurally diverse nitrosubstituted compounds, and for mutagenic translation bypass. Introduction of these plasmids into S. typhimurium TA1538 and TA1535 has created several new tester strains which exhibit an extremely high mutagenic sensitivity and a broad substrate specificity towards a battery of nitrosubstituted test compounds that included 4-nitroquinoline-1-oxide (4-NQO), nitrofurazone (NF), 1-nitropyrene (1-NP), 2-nitronaphthalene (2-NN), 2-nitrofluorene (2-NF), and 1,6-dinitropyrene (1,6-DNP). Our studies show that the nfsA gene encodes a product that is extremely effective in the metabolic activation of a range of structurally diverse nitrosubstituted compounds. Several of the new tester strains are more than two orders of magnitude more sensitive to nitrosubstituted compounds than the Ames tester strains TA100 or TA98. In addition to enhancing mutagenic sensitivity, plasmids encoding both metabolic and mutagenesis functions on a single plasmid provide considerable flexibility for future mechanistic studies or tester strain development, in which it may be necessary to introduce additional plasmids containing different antibiotic resistance markers. PMID:11934440

  17. Evaluation of the SOS chromotest for the detection of antimutagens

    SciTech Connect

    Sato, Takahiko; Chikazawa, Kazuhiko; Yamamori, Hidetomo; Ose, Youki; Nagase, Hisamitsu; Kito, Hideaki )

    1991-01-01

    The SOS chromotest was applied for the detection of antimutagens. To raise SOS induction, the bacteria were treated with the mutagens, UV, 4-nitroquinoline N-oxide (4NQO), N-methyl-N{prime}-nitro-N-nitroso-guanidine (MNNG), or benzo(a)pyrene (B(a)p). The inhibitory effects of {sub L}-ascorbic acid, glutathione, vanillin,5-fluorouracil (5-FU), 5-chlorouracil (5-CU), cobaltous chloride, sodium selenite and sodium arsenite, which are known as antimutagens, were investigated with their addition either simultaneously or post treatment time. In became clear that the SOS chromotest was very useful for the detection of antimutagens.

  18. Evaluation of the co-genotoxic effects of 1800 MHz GSM radiofrequency exposure and a chemical mutagen in cultured human cells

    NASA Astrophysics Data System (ADS)

    Perrin, Anne; Freire, Maëlle; Bachelet, Christine; Collin, Alice; Levêque, Philippe; Pla, Simon; Debouzy, Jean-Claude

    2010-11-01

    We investigated the effect of a 1800 MHz radiofrequency GSM signal combined with a known chemical mutagen (4-nitroquinoline-N-oxide: 4NQO) on human THP1 cells. Comet and γ-H2AX assays were used to assess DNA damage. No heating of the cell cultures was noted during exposure (2 h). The exposure of cells to electromagnetic fields with SARs of 2 to 16 W/kg did not increase the DNA damage induced by 4NQO, whereas the number of DNA strand breaks increased with a temperature increase of at least 4 °C. In conclusion, no co-genotoxic effect of radiofrequency was found at levels of exposure that did not induce heating.

  19. Effects of long-term administration of cancer-promoting substances on oral subepithelial mast cells in the rat.

    PubMed

    Sand, L; Hilliges, M; Larsson, P A; Wallstrom, M; Hirsch, J M

    2002-01-01

    The role of oral subepithelial mast cells in the defence against tumours is a matter of controversy. The effect of established and suggested carcinogens, such as the carcinogen 4-nitroquinoline-N-oxide (4-NQO) and Herpes simplex virus type 1 (HSV-1), in combination with oral snuff on lower lip subepithelial mast cells (MC) was studied in rats. The rats were exposed to prolonged use of oral snuff. The test substances were administered in a surgically created canal in the lower lip of the rats. There were 15 rats in each test group and 10 rats in the control group. The amount of countable subepithelial mast cells decreased significantly when the rat oral mucosa was exposed to the oral carcinogen 4-NQO but the effect of oral snuff and HSV-1 infection was weak. Our findings suggest that mast cells play a role in immunological cell defence against chemical carcinogens. Further studies are needed to clarify the mechanisms. PMID:12529973

  20. Isolation and analysis of UV and radio-resistant bacteria from Chernobyl.

    PubMed

    Zavilgelsky, G B; Abilev, S K; Sukhodolets, V V; Ahmad, S I

    1998-05-15

    The accident at the Chernobyl nuclear power station in 1986 led to the dispersal of large amounts of a variety of radioactive materials, most importantly uranium, plutonium, 137Cs, 131I and 90Sr, over very large distances estimated to reach as far as Sweden, Norway, Turkey and possibly the USA. As a consequence, the soil on which the radioactive materials fell was contaminated and the degree of contamination varied with distance from the station, the direction and strength of the wind and the amount of atmospheric scavenging by rainfall at that time. Some of the radioactive materials have left a significant impact on mankind in the form of chromosomal aberrations including trisomy, various forms of cancers and death, whilst others are still in the ground where they will remain for a prolonged period to continue to exert their effects. Likewise, microbes living in the soil and exposed to radioactive materials may have been affected in a number of ways; some perished, and others survived due to the acquisition of advantageous mutation. Six years after the accident, soil samples contaminated with different levels of radioactivity were obtained from five regions within a 30 km radius of the nuclear power plant. From these soil samples spore-forming bacilli were isolated, quantified, identified and tested for resistance to X-rays, UVC and 4-nitroquinoline 1-oxide (4NQO). As a control, spore-forming bacilli were obtained from 'Zeleny mys' (an area 50 km south-east of the power station and emitting basal levels of radioactivity). A mutant of Escherichia coli hyper-resistant to a variety of DNA-damaging agents and its parent strain were also included in the study. Analysis of results reveals that a proportion of isolates of the same species from near the power station and the E. coli mutant SA236 were more resistant to X-rays, UVC and 4NQO compared with isolates from the control site and the E. coli parent strain, KL14, respectively. PMID:9679315

  1. Isolation and analysis of UV and radio-resistant bacteria from Chernobyl.

    PubMed

    Zavilgelsky, G B; Abilev, S K; Sukhodolets, V V; Ahmad, S I

    1998-05-15

    The accident at the Chernobyl nuclear power station in 1986 led to the dispersal of large amounts of a variety of radioactive materials, most importantly uranium, plutonium, 137Cs, 131I and 90Sr, over very large distances estimated to reach as far as Sweden, Norway, Turkey and possibly the USA. As a consequence, the soil on which the radioactive materials fell was contaminated and the degree of contamination varied with distance from the station, the direction and strength of the wind and the amount of atmospheric scavenging by rainfall at that time. Some of the radioactive materials have left a significant impact on mankind in the form of chromosomal aberrations including trisomy, various forms of cancers and death, whilst others are still in the ground where they will remain for a prolonged period to continue to exert their effects. Likewise, microbes living in the soil and exposed to radioactive materials may have been affected in a number of ways; some perished, and others survived due to the acquisition of advantageous mutation. Six years after the accident, soil samples contaminated with different levels of radioactivity were obtained from five regions within a 30 km radius of the nuclear power plant. From these soil samples spore-forming bacilli were isolated, quantified, identified and tested for resistance to X-rays, UVC and 4-nitroquinoline 1-oxide (4NQO). As a control, spore-forming bacilli were obtained from 'Zeleny mys' (an area 50 km south-east of the power station and emitting basal levels of radioactivity). A mutant of Escherichia coli hyper-resistant to a variety of DNA-damaging agents and its parent strain were also included in the study. Analysis of results reveals that a proportion of isolates of the same species from near the power station and the E. coli mutant SA236 were more resistant to X-rays, UVC and 4NQO compared with isolates from the control site and the E. coli parent strain, KL14, respectively.

  2. Deletion of inositol hexakisphosphate kinase 1 (IP6K1) reduces cell migration and invasion, conferring protection from aerodigestive tract carcinoma in mice.

    PubMed

    Jadav, Rathan S; Kumar, Dharmika; Buwa, Natasha; Ganguli, Shubhra; Thampatty, Sitalakshmi R; Balasubramanian, Nagaraj; Bhandari, Rashna

    2016-08-01

    Inositol hexakisphosphate kinases (IP6Ks), a family of enzymes found in all eukaryotes, are responsible for the synthesis of 5-diphosphoinositol pentakisphosphate (5-IP7) from inositol hexakisphosphate (IP6). Three isoforms of IP6Ks are found in mammals, and gene deletions of each isoform lead to diverse, non-overlapping phenotypes in mice. Previous studies show a facilitatory role for IP6K2 in cell migration and invasion, properties that are essential for the early stages of tumorigenesis. However, IP6K2 also has an essential role in cancer cell apoptosis, and mice lacking this protein are more susceptible to the development of aerodigestive tract carcinoma upon treatment with the oral carcinogen 4-nitroquinoline-1-oxide (4NQO). Not much is known about the functions of the equally abundant and ubiquitously expressed IP6K1 isoform in cell migration, invasion and cancer progression. We conducted a gene expression analysis on mouse embryonic fibroblasts (MEFs) lacking IP6K1, revealing a role for this protein in cell receptor-extracellular matrix interactions that regulate actin cytoskeleton dynamics. Consequently, cells lacking IP6K1 manifest defects in adhesion-dependent signaling, evident by lower FAK and Paxillin activation, leading to reduced cell spreading and migration. Expression of active, but not inactive IP6K1 reverses migration defects in IP6K1 knockout MEFs, suggesting that 5-IP7 synthesis by IP6K1 promotes cell locomotion. Actin cytoskeleton remodeling and cell migration support the ability of cancer cells to achieve their complete oncogenic potential. Cancer cells with lower IP6K1 levels display reduced migration, invasion, and anchorage-independent growth. When fed an oral carcinogen, mice lacking IP6K1 show reduced progression from epithelial dysplasia to invasive carcinoma. Thus, our data reveal that like IP6K2, IP6K1 is also involved in early cytoskeleton remodeling events during cancer progression. However, unlike IP6K2, IP6K1 is essential for 4NQO

  3. Deletion of inositol hexakisphosphate kinase 1 (IP6K1) reduces cell migration and invasion, conferring protection from aerodigestive tract carcinoma in mice.

    PubMed

    Jadav, Rathan S; Kumar, Dharmika; Buwa, Natasha; Ganguli, Shubhra; Thampatty, Sitalakshmi R; Balasubramanian, Nagaraj; Bhandari, Rashna

    2016-08-01

    Inositol hexakisphosphate kinases (IP6Ks), a family of enzymes found in all eukaryotes, are responsible for the synthesis of 5-diphosphoinositol pentakisphosphate (5-IP7) from inositol hexakisphosphate (IP6). Three isoforms of IP6Ks are found in mammals, and gene deletions of each isoform lead to diverse, non-overlapping phenotypes in mice. Previous studies show a facilitatory role for IP6K2 in cell migration and invasion, properties that are essential for the early stages of tumorigenesis. However, IP6K2 also has an essential role in cancer cell apoptosis, and mice lacking this protein are more susceptible to the development of aerodigestive tract carcinoma upon treatment with the oral carcinogen 4-nitroquinoline-1-oxide (4NQO). Not much is known about the functions of the equally abundant and ubiquitously expressed IP6K1 isoform in cell migration, invasion and cancer progression. We conducted a gene expression analysis on mouse embryonic fibroblasts (MEFs) lacking IP6K1, revealing a role for this protein in cell receptor-extracellular matrix interactions that regulate actin cytoskeleton dynamics. Consequently, cells lacking IP6K1 manifest defects in adhesion-dependent signaling, evident by lower FAK and Paxillin activation, leading to reduced cell spreading and migration. Expression of active, but not inactive IP6K1 reverses migration defects in IP6K1 knockout MEFs, suggesting that 5-IP7 synthesis by IP6K1 promotes cell locomotion. Actin cytoskeleton remodeling and cell migration support the ability of cancer cells to achieve their complete oncogenic potential. Cancer cells with lower IP6K1 levels display reduced migration, invasion, and anchorage-independent growth. When fed an oral carcinogen, mice lacking IP6K1 show reduced progression from epithelial dysplasia to invasive carcinoma. Thus, our data reveal that like IP6K2, IP6K1 is also involved in early cytoskeleton remodeling events during cancer progression. However, unlike IP6K2, IP6K1 is essential for 4NQO

  4. Chemoprevention of oral cancer in animal models, and effect on leukoplakias in human patients with ZengShengPing, a mixture of medicinal herbs.

    PubMed

    Sun, Zheng; Guan, Xiaobing; Li, Ning; Liu, Xiaoyong; Chen, Xiaoxin

    2010-02-01

    ZengShengPing (ZSP), a mixture of six medicinal herbs, has been reported to prevent esophageal squamous cell carcinoma (SCC) in human patients with dysplasia. This study was designed to investigate the chemopreventive effects of ZSP on oral cancer in animal models and human patients. In the 7,12-dimethylbenz[a]anthracene (DMBA)-induced hamster cheek pouch model, ZSP (6g/kgBW/day by gavage for 10 weeks) significantly reduced the number of visible tumor, the tumor volume, and the incidence of SCC (P<0.01). Two biomarkers associated with cell proliferation, silver stained nucleolar organizer region (AgNOR) and proliferating cell nuclear antigen (PCNA)-labeling index, were also significantly suppressed by ZSP treatment (P<0.01). In the 4-nitroquinoline 1-oxide (4NQO)-induced oro-esophageal cancer model in mice, ZSP (10% in diet) also significantly reduced the incidence of tongue SCC from 55.2% (16/29) to 22.2% (6/27) (P<0.05), and slightly reduced the incidence of esophageal SCC from 34.5% (10/29) to 22.2% (6/27). Furthermore, in a randomized clinical trial on patients with oral leukoplakia, ZSP (4 tablets, 3 times per day for 8-12months) reduced the size of oral lesion in 67.8% (40/59) patients, whereas the placebo was effective in 17% (9/53) patients (P<0.01). Such an effect was associated with significant decrease of AgNOR and PCNA-labeling index. In summary, our studies have demonstrated the chemopreventive effects of ZSP on two animal models of oral cancer, and human patients with oral leukoplakia. PMID:20022553

  5. Relationship of DNA repair processes to mutagenesis and carcinogenesis in mammalian cells. Progress report, November 1, 1979-October 31, 1980

    SciTech Connect

    Evans, H.H.

    1980-10-01

    The objective of this research is to determine the role of DNA repair in mutagenesis and carcinogenesis in mammalian cells. Use of the host-cell reactivation viral suicide enrichment procedure was initiated in the isolation of repair-deficient mutants. Lightly mutagenized BHK cells were infected with irradiated Herpes simplex virus (HSV); several radiation-sensitive strains were isolated among the survivors of the infection. The characterization of these strains is progressing and the enrichments are continuing. That alterations in the frequency of mutation of C3H/10T 1/2 cells, occurring as a result of holding the cells in a confluent state following treatment with ethylmethane sulfonate, parallel the alterations in the frequency of neoplastic transformation was found. The repair capabilities of BHK cells were found to be intermediate in comparison to repair-proficient and -deficient human cells with regard to the reactivation of HSV treated with various inactivating agents. The effect of confluency and of low serum levels on DNA synthesis, as well as the response to the cytotoxic effects of MNNG and acriflavin were determined in BHK cells in preparation for the investigation of the role of DNA repair in mutagenesis and transformation. It was also found that C3H/10T 1/2 cells partially recover from the toxic effects of 4-nitroquinoline-1-oxide if they are held in a confluent state for 6 to 22 hrs following treatment. Addition of catalase did not alleviate the toxic effects of 4-NQO. The cells contain a relatively high endogenous level of this enzyme. (ERB)

  6. Nitrocompound activation by cell-free extracts of nitroreductase-proficient Salmonella typhimurium strains.

    PubMed

    Salamanca-Pinzón, S G; Camacho-Carranza, R; Hernández-Ojeda, S L; Espinosa-Aguirre, J J

    2006-11-01

    A characterization of nitrocompounds activation by cell-free extracts (CFE) of wild-type (AB(+)), SnrA deficient (B(+)), Cnr deficient (A(+)) and SnrA/Cnr deficient (AB(-)) Salmonella typhimurium strains has been done. The Ames mutagenicity test (S. typhimurium his(+) reversion assay) was used, as well as nitroreductase (NR) activity determinations where the decrease in absorbance generated by nitrofurantoin (NFN) reduction and NADP(H) oxidation in the presence of NFN, nitrofurazone (NFZ), metronidazole (MTZ) and 4-nitroquinoline-1-oxide (4NQO) were followed. Different aromatic and heterocyclic compounds were tested for mutagenic activation: 2-nitrofluorene (2-NF); 2,7-dinitrofluorene (2,7-DNF); 1-nitropyrene (1-NP), 1,3-dinitropyrene (1,3-DNP); 1,6-dinitropyrene (1,6-DNP); and 1,8-dinitropyrene (1,8-DNP). Differential mutagenicity was found with individual cell free extracts, being higher when the wild type or Cnr containing extract was used; nevertheless, depending on the nitrocompound, activation was found when either NR, SnrA or Cnr, were present. In addition, all nitrocompounds were more mutagenic after metabolic activation by CFE of NR proficient strains, although AB(-) extract still showed activation capacity. On the other hand, NR activity was predominantly catalyzed by wild type CFE followed by A(+), B(+) and AB(-) extracts in that order. We can conclude that results from the Ames test indicate that Cnr is the major NR, while NFN and NFZ reductions were predominantly catalyzed by SnrA. The characterization of the residual NR activity detected by the mutagenicity assay and the biochemical determinations in the AB(-) CFE needs further investigation. PMID:16998228

  7. Induction and repair of DNA damage measured by the comet assay in human T lymphocytes separated by immunomagnetic cell sorting.

    PubMed

    Bausinger, Julia; Speit, Günter

    2014-11-01

    The comet assay is widely used in human biomonitoring to measure DNA damage in whole blood or isolated peripheral blood mononuclear cells (PBMC) as a marker of exposure to genotoxic agents. Cytogenetic assays with phytohemagglutinin (PHA)-stimulated cultured T lymphocytes are also frequently performed in human biomonitoring. Cytogenetic effects (micronuclei, chromosome aberrations, sister chromatid exchanges) may be induced in vivo but also occur ex vivo during the cultivation of lymphocytes as a consequence of DNA damage present in lymphocytes at the time of sampling. To better understand whether DNA damage measured by the comet assay in PBMC is representative for DNA damage in T cells, we comparatively investigated DNA damage and its repair in PBMC and T cells obtained by immunomagnetic cell sorting. PBMC cultures and T cell cultures were exposed to mutagens with different modes of genotoxic action and DNA damage was measured by the comet assay after the end of a 2h exposure and after 18h post-incubation. The mutagens tested were methyl methanesulfonate (MMS), (±)-anti-B[a]P-7,8-dihydrodiol-9,10-epoxide (BPDE), 4-nitroquinoline-1-oxide (4NQO), styrene oxide and potassium bromate. MMS and potassium bromate were also tested by the modified comet assay with formamido pyrimidine glycosylase (FPG) protein. The results indicate that the mutagens tested induce DNA damage in PBMC and T cells in the same range of concentrations and removal of induced DNA lesions occurs to a comparable extent. Based on these results, we conclude that the comet assay with PBMC is suited to predict DNA damage and its removal in T cells.

  8. Protection against malignant conversion of chemically induced benign skin papillomas to squamous cell carcinomas in SENCAR mice by a polyphenolic fraction isolated from green tea.

    PubMed

    Katiyar, S K; Agarwal, R; Mukhtar, H

    1993-11-15

    Progression of benign tumors to malignant cancer is critical since cancerous lesions are capable of metastatic spread and eventually causing death. Inhibitors of the conversion process, therefore, would likely be useful as cancer chemopreventive agents. In this study, we assessed the protective effect of topical application of a polyphenolic fraction isolated from green tea (GTP) against spontaneous as well as benzoyl peroxide (BPO)- and 4-nitroquinoline-N-oxide (4-NQO)-enhanced malignant conversion of chemically induced skin papillomas in SENCAR mice. Papillomas were induced in SENCAR mice by topical application of 7,12-dimethylbenz(a)anthracene as a tumor-initiating agent followed by twice a week application of 12-O-tetradecanoylphorbol-13-acetate as a tumor-promoting agent. Beginning at the 20th week, when papilloma yield was stabilized, enhanced malignant conversion was achieved by twice weekly topical application of either BPO or 4-NQO, whereas spontaneous malignant conversion was associated with topical application of acetone. In these protocols, preapplication of GTP (6 mg/animal) 30 min prior to skin application of acetone, BPO, or 4-NQO resulted in 14, 31, and 29% protection, respectively, in terms of percentage of mice with carcinomas, and 20, 35, and 43% protection in terms of number of carcinomas/mouse. In these experiments, a BPO- and 4-NQO-enhanced rate of malignant conversion was also found to be decreased significantly by the skin application of GTP; however, such effects of GTP were less profound in the cases of spontaneous malignant conversion. The results of this study suggest that, in addition to its chemopreventive effects against tumor initiation and promotion stages of multistage carcinogenesis, green tea also possesses significant protective effects against tumor progression, specifically tumor progression induced by BPO and 4-NQO.

  9. [Inhibitory effects of fifteen kinds of Chinese herbal drugs, vegetables and chemicals on SOS response].

    PubMed

    Jin, Z C; Qian, J

    1994-05-01

    Effects of 15 kinds of herbal drugs, vegetables and chemicals on lex-dependent sfi-SOS response were determined by micropersistent and/or pulse models induced by 4-Nitroquinoline-N-oxide (4NQO) and Mitomycin C (MMC) in Escherichia coli(E. coli) PQ37 and PQ35, respectively. Results showed the water extract of Rhizoma Polygonati (RP), Fructus Chebulae (FC), Radix Polygoni Multiflori (RPM), Fructus Ligustri Lucidi (FLL), Bulbus Fritillariae Thunbergii (BFT), shell of water chestnut with a pedicle, Chinese chives juice, and solutions of 5-Fluorouracil, Tannic acid and garlicin could inhibit SOS responses with a dose-response relationship and suggested the inhibitory effects took place both inside and outside E. coli cells. Water extract of FC, FLL, BFT, shell of water chestnut with a pedicle, Chinese chives juice and solution of 5-Fluorouracil and Tannic acid could intracellularly inhibit SOS responses induced by MMC in E. coli PQ35, and acetone extract of Grifola Frondosa (GF) could extracellularly inhibit SOS responses in E. coli PQ37 and intracellularly in PQ35 induced by 4NQO or MMC. Water extract of raw hawthorn. Radix Angelicae Duhuricae (RAD), Radix Ophiopogonis (RO), and 5-Fluorodeoxyuridine could extracellularly inhibit SOS responses induced by 4NQO in E coli PQ37. The possible mechanisms of intracellular inhibition and antidamage repair were discussed in the paper.

  10. Modulation of mutagenicity of various mutagens by lignin derivatives.

    PubMed

    Mikulásová, Mária; Kosíková, Bozena

    2003-03-01

    The effect of lignin on cytotoxicity, mutagenicity and SOS response induced by 4-nitroquinoline-N-oxide (4NQO), 3-(5-nitro-2-furyl)acrylic acid (5NFAA), 2-nitrofluorene (2NF) as well as hydrogen peroxide was investigated in bacterial assay systems, i.e. the Ames test with Salmonella typhimurium TA98, TA100, TA102 and the SOS chromotest with Escherichia coli PQ37. Lignin preparations obtained from beech wood significantly decreased the mutagenicity induced by 4NQO, 2NF and H(2)O(2). In the case of mutagenicity induced by 5NFAA the effect was lower. Antimutagenic properties of lignin samples tested were shown also by SOS chromotest where lignin inhibited the ability of both 4NQO and H(2)O(2) to induce the SOS response. Derivatives of lignin including those from soft and hard wood, as well as from annual plants differ in their efficiency to inhibit the induction of the SOS response. The modified lignins isolated from beech and spruce wood exhibit a high level of protection. Lignins from annual plants-corn cobs and straw-only marginally evoked an antimutagenic response, but their effect was increased by hydrothermic treatment of both annual plants. The results obtained indicate the prospective utilization of lignin preparations as additive in chemo-prevention. The antimutagenic effect of lignin samples varies with the method of isolation and modification, as well as with the genetic origin of the lignin. PMID:12581535

  11. Genotoxicity of dental resin polymerization initiators in vitro.

    PubMed

    Nomura, Y; Teshima, W; Kawahara, T; Tanaka, N; Ishibashi, H; Okazaki, M; Arizono, K

    2006-01-01

    The polymerization initiators for resins cured using visible light usually consist of a photosensitizer, primarily camphorquinone (CQ), and a reducing agent, which is often a tertiary amine (DMPT, DMAEMA), while the initiator used for self-curing resins consists of benzoyl peroxide (BPO) and a tertiary amine (DMPT). The genotoxicities of camphorquinone (CQ), benzoyl peroxide (BPO), dimethyl-para-toluidine (DMPT), 2-dimethylamino-ethyl-methacrylate (DMAEMA), and 1-allyl-2-thiourea (ATU) were examined using the bioluminescent bacterial genotoxicity test. 4-Nitroquinoline-N-oxide (4NQO) was prepared for comparison with these chemicals. Acetone solutions of the five polymerization initiators and 4NQO were prepared. Benzoyl peroxide (BPO), dimethyl-para-toluidine (DMPT), and 1-allyl-2-thiourea (ATU) showed significant genotoxic activity at 24 h in the bioluminescent bacterial genotoxicity test, at concentrations of approximately 5 microM, 4 mM, and 1 mM, respectively. 2-Dimethyloamino-ethyl-methacrylate (DMAEMA) did not have genotoxic activity and CQ had questionable genotoxic activity. In comparison, 4NQO had strong genotoxicity, at 4 microM, roughly the same as that of BPO. Therefore, BPO should be used carefully in clinical dentistry.

  12. Synergistic effect of isopropanol on induction of mitotic aberrations in Allium cepa

    SciTech Connect

    Jacobs, S.; Meier, J.R.; Smith, M.K.

    1995-12-31

    Soil from a site heavily contaminated with polychlorinated biphenyls and several other organic and inorganic compounds was remediated by treatment with a mobile solvent extraction system. The genotoxicity of the soil, as measured by the induction of anaphase aberrations in Allium cepa root tip cells, increased after the remediation process. This increase appeared to be due to synergism between the residual solvent and genotoxic components not removed by the solvent extraction process. The purpose of the present study was to determine whether isopropanol, at concentrations similar to residual amounts following remediation, induced a synergistic response with the known clastogen, 4-nitroquinoline n-oxide (4-NQO). Bulblets of Allium cepa (common onion) were exposed for 24 h to varying concentrations of isopropanol combined with 0.10 g/l 4-NQO in aqueous solution. The root tips were examined for mitotic index (MI), and cells in late anaphase/early telophase were scored for mitotic aberrations. MI and MA frequencies were transformed by the arcsin square root function prior to statistical analysis (ANOVA). Isopropanol by itself did not induce MA and did not affect the MI, either alone or in combination with 4-NQO. However, isopropanol enhanced the 4-NQO-induced MA response by 1.4 fold at 1.0 mg/ml (p-value = 0.13) and 2.0 fold at 1.2 mg/ml (p-value = 0.006). Lower concentrations of 0.3 and 0.1 mg/ml isopropanol had no effect. The results demonstrate that residual solvents can increase the genotoxicity of soils, presumably as a result of enhancing the bioavailability of genotoxic components.

  13. Carcinogenic responses to chemicals applied directly to rat mammary glands in situ

    SciTech Connect

    Holtzman, S.; Meade, M.; Stone, J.P.; Shellabarger, C.J.

    1985-01-01

    In four experiments, concentrated glycerin suspensions of 7,12-dimethylbenz(a)anthracene (DMBA), or the water-soluble compounds, N-methyl-N-nitrosourea (MNU), N-ethyl-N-nitrosourea (ENU), and 4-nitroquinoline-N-oxide (4-NQO) were delivered into pockets in the mammary fat pads in female Sprague-Dawley rats. In a 90-day experiment, each of three groups of 20-22 rats were treated with either 25, 50, or 100 ..mu..g DMBA delivered to each of four sites in each rat per group. Dose-related responses were detected for incidence of rats with mammary adenocarcinoma (MAC), and for number of MAC per treated site. In a 120-day study, each of three groups of 20 animals were treated with either 250, 500, or 1000 ..mu..g MNU at each of 80 sites per group. Dose-related MAC responses were detected for incidence of rats with MAC, number of MAC per treated site, and time to detection of MAC. In two experiments of 90 days duration, groups of 20 females were treated with either 1000 ..mu..g ENU or 1000 ..mu..g 4-NQO at each of 80 sites per group. ENU produced a total of 27 MAC sites in 65% of the rats, and 4-NQO produced a total of 26 MAC in 60% of the rats. A comparison of the time to detection of all MAC data for the three water-soluble compounds at the 1000 ..mu..g treatment level, or on the basis of moles per treatment, yielded a carcinogenic potency relationship of 4-NQO > ENU > MNU. 21 references, 2 figures, 1 table.

  14. [In vitro and in vivo photochemical reactivity of methaqualone-1-oxide].

    PubMed

    Pöhlmann, H; Theil, F P; Franke, P; Pfeifer, S

    1986-12-01

    Methaqualone-1-oxide (1) exhibits photochemical reactivity. By irradiation of 1 with solar light the oxaziridin 3 is formed at first, which reacts in vitro (human proteins) and in vivo (rats) with macromolecules. As result of the photochemical in vitro and in vivo reactions of 1 the photoproduct 2-acetamidobenzoic acid-2'-methylanilide (6), involved in oxidation of protic compounds, was detected and after hydrolysis of proteins it appears that the short-lived 3 was adding to proteins.

  15. Resting potential, oncogene-induced tumorigenesis, and metastasis: the bioelectric basis of cancer in vivo

    NASA Astrophysics Data System (ADS)

    Lobikin, Maria; Chernet, Brook; Lobo, Daniel; Levin, Michael

    2012-12-01

    Cancer may result from localized failure of instructive cues that normally orchestrate cell behaviors toward the patterning needs of the organism. Steady-state gradients of transmembrane voltage (Vmem) in non-neural cells are instructive, epigenetic signals that regulate pattern formation during embryogenesis and morphostatic repair. Here, we review molecular data on the role of bioelectric cues in cancer and present new findings in the Xenopus laevis model on how the microenvironment's biophysical properties contribute to cancer in vivo. First, we investigated the melanoma-like phenotype arising from serotonergic signaling by ‘instructor’ cells—a cell population that is able to induce a metastatic phenotype in normal melanocytes. We show that when these instructor cells are depolarized, blood vessel patterning is disrupted in addition to the metastatic phenotype induced in melanocytes. Surprisingly, very few instructor cells need to be depolarized for the hyperpigmentation phenotype to occur; we present a model of antagonistic signaling by serotonin receptors that explains the unusual all-or-none nature of this effect. In addition to the body-wide depolarization-induced metastatic phenotype, we investigated the bioelectrical properties of tumor-like structures induced by canonical oncogenes and cancer-causing compounds. Exposure to carcinogen 4-nitroquinoline 1-oxide (4NQO) induces localized tumors, but has a broad (and variable) effect on the bioelectric properties of the whole body. Tumors induced by oncogenes show aberrantly high sodium content, representing a non-invasive diagnostic modality. Importantly, depolarized transmembrane potential is not only a marker of cancer but is functionally instructive: susceptibility to oncogene-induced tumorigenesis is significantly reduced by forced prior expression of hyperpolarizing ion channels. Importantly, the same effect can be achieved by pharmacological manipulation of endogenous chloride channels, suggesting

  16. Study of the DNA damage checkpoint using Xenopus egg extracts.

    PubMed

    Willis, Jeremy; DeStephanis, Darla; Patel, Yogin; Gowda, Vrushab; Yan, Shan

    2012-01-01

    On a daily basis, cells are subjected to a variety of endogenous and environmental insults. To combat these insults, cells have evolved DNA damage checkpoint signaling as a surveillance mechanism to sense DNA damage and direct cellular responses to DNA damage. There are several groups of proteins called sensors, transducers and effectors involved in DNA damage checkpoint signaling (Figure 1). In this complex signaling pathway, ATR (ATM and Rad3-related) is one of the major kinases that can respond to DNA damage and replication stress. Activated ATR can phosphorylate its downstream substrates such as Chk1 (Checkpoint kinase 1). Consequently, phosphorylated and activated Chk1 leads to many downstream effects in the DNA damage checkpoint including cell cycle arrest, transcription activation, DNA damage repair, and apoptosis or senescence (Figure 1). When DNA is damaged, failing to activate the DNA damage checkpoint results in unrepaired damage and, subsequently, genomic instability. The study of the DNA damage checkpoint will elucidate how cells maintain genomic integrity and provide a better understanding of how human diseases, such as cancer, develop. Xenopus laevis egg extracts are emerging as a powerful cell-free extract model system in DNA damage checkpoint research. Low-speed extract (LSE) was initially described by the Masui group. The addition of demembranated sperm chromatin to LSE results in nuclei formation where DNA is replicated in a semiconservative fashion once per cell cycle. The ATR/Chk1-mediated checkpoint signaling pathway is triggered by DNA damage or replication stress. Two methods are currently used to induce the DNA damage checkpoint: DNA damaging approaches and DNA damage-mimicking structures. DNA damage can be induced by ultraviolet (UV) irradiation, γ-irradiation, methyl methanesulfonate (MMS), mitomycin C (MMC), 4-nitroquinoline-1-oxide (4-NQO), or aphidicolin. MMS is an alkylating agent that inhibits DNA replication and activates the ATR

  17. Antimutagenic activity of phenylpropanoids from clove (Syzygium aromaticum).

    PubMed

    Miyazawa, Mitsuo; Hisama, Masayoshi

    2003-10-22

    Phenylpropanoids that possess antimutagenic activity were isolated from the buds of clove (Syzygium aromaticum). The isolated compounds suppressed the expression of the umu gene following the induction of SOS response in the Salmonella typhimurium TA1535/pSK1002 that have been treated with various mutagens. The suppressive compounds were mainly localized in the ethyl acetate extract fraction of the processed clove. This ethyl acetate fraction was further fractionated by silica gel column chromatography, which resulted in the purification and subsequent identification of the suppressive compounds. Electron impact mass spectrometry, IR, and (1)H and (13)C NMR spectroscopy were then used to delineate the structures of the compounds that confer the observed antimutagenic activity. The secondary suppressive compounds were identified as dehydrodieugenol (1) and trans-coniferyl aldehyde (2). When using 2-(2-furyl)-3-(5-nitro-2-furyl)acrylamide (furylfuramide) as the mutagen, compound 1 suppressed 58% of the umu gene expression as compared to the controls at a concentration of 0.60 micromol/mL, with an ID(50) (50% inhibitory dose) value of 0.48 micromol/mL, and compound 2 suppressed 63% of the umu gene expression as compared to the controls at a concentration of 1.20 micromol/mL, with an ID(50) value of 0.76 micromol/mL. Additionally, compounds 1 and 2 were tested for their ability to suppress the mutagenic activity of other well-known mutagens such as 4-nitroquinolin 1-oxide (4NQO) and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), which do not require liver metabolizing enzymes, and aflatoxin B(1) (AfB(1)) and 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1), which require liver metabolizing enzymes and activated Trp-P-1 and UV irradiation. Compounds 1 and 2 showed dramatic reductions in their mutagenic potential of all of the aforementioned chemicals or treatment. For the search of the structure-activity relationship, the derivatives of 1 and 2 (1a and 2a-c) were

  18. Resting Potential, Oncogene-induced Tumorigenesis, and Metastasis: The Bioelectric Basis of Cancer in vivo

    PubMed Central

    Lobikin, Maria; Chernet, Brook; Lobo, Daniel; Levin, Michael

    2012-01-01

    Cancer may result from localized failure of instructive cues that normally orchestrate cell behaviors towards the patterning needs of the organism. Steady-state gradients of transmembrane voltage (Vmem) in non-neural cells are instructive, epigenetic signals that regulate pattern formation during embryogenesis and morphostatic repair. Here, we review molecular data on the role of bioelectric cues in cancer and present new findings in the Xenopus laevis model on how the microenvironment’s biophysical properties contribute to cancer in vivo. First, we investigated the melanoma-like phenotype arising from serotonergic signaling by “instructor” cells – a cell population that is able to induce a metastatic phenotype in normal melanocytes. We show that when these instructor cells are depolarized, blood vessel patterning is disrupted in addition to the metastatic phenotype induced in melanocytes. Surprisingly, very few instructor cells need to be depolarized for the hyperpigmentation phenotype to occur; we present a model of antagonistic signaling by serotonin receptors that explains the unusual all-or-none nature of this effect. In addition to the body-wide depolarization-induced metastatic phenotype, we investigated the bioelectrical properties of tumor-like structures induced by canonical oncogenes and cancer-causing compounds. Exposure to carcinogen 4-Nitroquinoline 1-oxide (4NQO) induces localized tumors, but has a broad (and variable) effect on the bioelectric properties of the whole body. Tumors induced by oncogenes show aberrantly high sodium content, representing a non-invasive diagnostic modality. Importantly, depolarized transmembrane potential is not only a marker of cancer but is functionally instructive: susceptibility to oncogene-induced tumorigenesis is significantly reduced by forced prior expression of hyperpolarizing ion channels. Importantly, the same effect can be achieved by pharmacological manipulation of endogenous chloride channels

  19. Resting potential, oncogene-induced tumorigenesis, and metastasis: the bioelectric basis of cancer in vivo.

    PubMed

    Lobikin, Maria; Chernet, Brook; Lobo, Daniel; Levin, Michael

    2012-12-01

    Cancer may result from localized failure of instructive cues that normally orchestrate cell behaviors toward the patterning needs of the organism. Steady-state gradients of transmembrane voltage (V(mem)) in non-neural cells are instructive, epigenetic signals that regulate pattern formation during embryogenesis and morphostatic repair. Here, we review molecular data on the role of bioelectric cues in cancer and present new findings in the Xenopus laevis model on how the microenvironment's biophysical properties contribute to cancer in vivo. First, we investigated the melanoma-like phenotype arising from serotonergic signaling by 'instructor' cells-a cell population that is able to induce a metastatic phenotype in normal melanocytes. We show that when these instructor cells are depolarized, blood vessel patterning is disrupted in addition to the metastatic phenotype induced in melanocytes. Surprisingly, very few instructor cells need to be depolarized for the hyperpigmentation phenotype to occur; we present a model of antagonistic signaling by serotonin receptors that explains the unusual all-or-none nature of this effect. In addition to the body-wide depolarization-induced metastatic phenotype, we investigated the bioelectrical properties of tumor-like structures induced by canonical oncogenes and cancer-causing compounds. Exposure to carcinogen 4-nitroquinoline 1-oxide (4NQO) induces localized tumors, but has a broad (and variable) effect on the bioelectric properties of the whole body. Tumors induced by oncogenes show aberrantly high sodium content, representing a non-invasive diagnostic modality. Importantly, depolarized transmembrane potential is not only a marker of cancer but is functionally instructive: susceptibility to oncogene-induced tumorigenesis is significantly reduced by forced prior expression of hyperpolarizing ion channels. Importantly, the same effect can be achieved by pharmacological manipulation of endogenous chloride channels, suggesting a

  20. Investigation of the antimutagenic effects of selected South African medicinal plant extracts.

    PubMed

    Verschaeve, L; Kestens, V; Taylor, J L S; Elgorashi, E E; Maes, A; Van Puyvelde, L; De Kimpe, N; Van Staden, J

    2004-02-01

    Dichloromethane extracts from different parts of Rhamnus prinoides, Ornithogalum longibracteatum, Gardenia volkensii, Spirostachys africana, Diospyros whyteana, Syzigium cordatum and Prunus africana were investigated for mutagenic and antimutagenic effects in Salmonella/microsome and micronucleus tests. None of the extracts tested in the Ames test were found to induce mutations or to modify the effect of the mutagen 4-nitroquinoline-oxide (4NQO). In the micronucleus test, extracts from twigs/bark of R. prinoides, twigs of D. whyteana, P. africana and S. cordatum significantly lowered the effect of the mutagen mitomycin C (MMC). Extracts from twigs/bark of G. volkensii and S. africana were genotoxic in the micronucleus test, while extracts of O. longibracteatum leaves potentiated the genotoxicity of MMC. This preliminary investigation shows that plant extracts used in traditional medicine may have particular effects with regard to mutagenicity and antimutagenicity indicating careful use in some instances and the need to isolate their active principles for further research.

  1. Antimutagens in gaiyou (Artemisia argyi levl. et vant.).

    PubMed

    Nakasugi, T; Nakashima, M; Komai, K

    2000-08-01

    Antimutagens from gaiyou (Artemisia argyi Levl. et Vant., Compositae) were examined. The methanol extract prepared from aerial parts of this plant strongly reduced the mutagenicity of 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2), when Salmonella typhimurium TA98 was used in the presence of the rat liver microsomal fraction. The antimutagens were purified chromatographically while monitoring the antimutagenic activity against Trp-P-2 with a modified Ames test employing a plate method. This purification resulted in the isolation of four strong antimutagens, 5,7-dihydroxy-6,3',4'-trimethoxyflavone (eupatilin), 5, 7,4'-trihydroxy-6,3'-dimethoxyflavone (jaceosidin), 5,7, 4'-trihydroxyflavone (apigenin) and 5,7, 4'-trihydroxy-3'-methoxyflavone (chrysoeriol) from the methanol extract. These antimutagenic flavones exhibited strong antimutagenic activity against not only Trp-P-2 but also against other heterocyclic amines, such as 3-amino-1,4-dimethyl-5H-pyrido[4, 3-b]indole (Trp-P-1), 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ), 2-amino-3, 8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) and 2-amino-3-methyl-9H-pyrido[2,3-b]indole (MeA(alpha)C) in S. typhimurium TA98. In contrast, they did not exhibit antimutagenic activity against benzo[a]pyrene (B[a]P), 4-nitroquinoline-1-oxide (4-NQO), 2-aminofluorene (2-AF), 2-nitrofluorene (2-NF) or furylfuramide (AF-2) in S. typhimurium TA98, or B[a]P, 4-NQO, 2-NF, AF-2, N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) or sodium azide (SA) in Salmonella typhimurium TA100, whereas they decreased the mutagenicity caused by aflatoxin B(1) (AFB(1)) and 2-aminoanthracene (2-AA) in both of these tester strains. Regarding the structure-activity relationship, the tested flavones had distinct differences in the intensities of their antimutagenic activities according to the differences of their substitution patterns. Namely, the intensity of antimutagenic activities against Trp-P-2 decreased in

  2. Triazene 1-oxide compounds: Synthesis, characterization and evaluation as fluorescence sensor for biological applications

    NASA Astrophysics Data System (ADS)

    dos Santos, Aline Joana Rolina Wohlmuth Alves; Bersch, Patrícia; de Oliveira, Huéder Paulo Moisés; Hörner, Manfredo; Paraginski, Gustavo Luiz

    2014-02-01

    Triazene compounds have been known for over 100 years. This class of compounds is versatile because they have different applications as chemical and biological reagents. Currently, the tendency of applications of triazenes is as fluorescence sensors with biological and environmental functions. This work discusses the synthesis and structural characterization through IR, MS (EI), 13C NMR, 1H NMR, DSC and TGA analyzes of two triazene compounds, namely, 1-methyl-3-(p-carboxyphenyl)triazene 1-oxide (1) and 1-methyl-3-(phenyl)triazene 1-oxide (2). A comparative fluorescence study between these triazenes as potential compounds for application in the chemical sensors has also been carried out. The molecular and supramolecular structure of compound (1) is also determined by X-ray diffraction on single crystal, where the classic hydrogen bonds give the tridimensional arrangement. The presence of para-carboxylic group in compound (1) as well as the polarity and viscosity of the tested organic solvents resulted in a great influence on the evaluation of the fluorescence effect. These experimental findings show the potential use of triazenes as fluorescent biosensors, since the compounds (1) and (2) present antimicrobial activity.

  3. Sensitivity of 2,6-Diamino-3, 5-Dinitropyrazine-1-Oxide

    SciTech Connect

    Tarver, C M; Urtiew, P A; Tran, T D

    2005-01-20

    The thermal and shock sensitivities of plastic bonded explosive formations based on 2,6-diamino-3,5-dinitropyrazine-1-oxide (commonly called LLM-105 for Lawrence Livermore Molecule No.105) are reported. The One Dimensional Time to Explosion (ODTX) apparatus was used to generate times to thermal explosion at various initial temperatures. A four-reaction chemical decomposition model was developed to calculate the time to thermal explosion versus inverse temperature curve. Three embedded manganin pressure gauge experiments were fired at different initial pressures to measure the pressure buildup and the distance required for transition to detonation. An Ignition and Growth reactive model was calibrated to this shock initiation data. LLM-105 exhibited thermal and shock sensitivities intermediate between those of triaminotrinitrobenzene (TATB) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazine (HMX).

  4. Synergistic effect of isopropanol on induction of mitotic aberrations in Allium cepa

    SciTech Connect

    Jacobs, S.; Meier, J.R.; Smith, M.K.; Torsella, J.

    1995-12-31

    Soil from a site heavily contaminated with polychlorinated biphenyls and several other organic and inorganic compounds was remediated by treatment with a mobile solvent extraction system. The genotoxicity of the soil, as measured by the induction of anaphase aberrations in Allium cepa root tip cells, increased after the remediation process. This increase appeared to be due to synergism between the residual solvent and genotoxic components not removed by the solvent extraction process. The purpose of the present study was to determine whether isopropanol, at concentrations similar to residual amounts following remediation, induced a synergistic response with the known clastogen, 4-nitroquinoline n-oxide (4-NQO). Bulblets of Allium cepa (common onion) were exposed for 24 h to varying concentrations of isopropanol combined with 0.10 mg/14-NQO in aqueous solution. The root tips were examined for mitotic index (MI), and cells in late anaphase/early telophase were scored for mitotic aberrations (MA, i.e., bridges, fragments, and lagging chromosomes). MI and MA frequencies were transformed by the arcsin square root function prior to statistical analysis (ANOVA). Isopropanol by itself did not induce MA and did not affect the Ml, either alone or in combination with 4-NQO. However, isopropanol enhanced the 4-NQO induced MA response by 1.4 fold at 1.0 mg/ml (p-value = 0.13) and 2.0 fold at 1.2 mg/ml (p-value = 0.006). Lower concentrations of 0.3 and 0.1 mg/ml isopropanol had no effect. The results demonstrate that residual solvents can increase the genotoxicity of soils, presumably as a result of enhancing the bioavailability of genotoxic components.

  5. 49 CFR 173.152 - Exceptions for Division 5.1 (oxidizers) and Division 5.2 (organic peroxides).

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Division 5.2 (organic peroxides). 173.152 Section 173.152 Transportation Other Regulations Relating to... Exceptions for Division 5.1 (oxidizers) and Division 5.2 (organic peroxides). (a) General. Exceptions for.... Limited quantities of oxidizers (Division 5.1) in Packing Group II and III and organic peroxides...

  6. 49 CFR 173.152 - Exceptions for Division 5.1 (oxidizers) and Division 5.2 (organic peroxides).

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Division 5.2 (organic peroxides). 173.152 Section 173.152 Transportation Other Regulations Relating to... Exceptions for Division 5.1 (oxidizers) and Division 5.2 (organic peroxides). (a) General. Exceptions for.... Limited quantities of oxidizers (Division 5.1) in Packing Group II and III and organic peroxides...

  7. 49 CFR 173.152 - Exceptions for Division 5.1 (oxidizers) and Division 5.2 (organic peroxides).

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Division 5.2 (organic peroxides). 173.152 Section 173.152 Transportation Other Regulations Relating to... Exceptions for Division 5.1 (oxidizers) and Division 5.2 (organic peroxides). (a) General. Exceptions for.... Limited quantities of oxidizers (Division 5.1) in Packing Group II and III and organic peroxides...

  8. 49 CFR 173.152 - Exceptions for Division 5.1 (oxidizers) and Division 5.2 (organic peroxides).

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Division 5.2 (organic peroxides). 173.152 Section 173.152 Transportation Other Regulations Relating to... Exceptions for Division 5.1 (oxidizers) and Division 5.2 (organic peroxides). (a) General. Exceptions for.... Limited quantities of oxidizers (Division 5.1) in Packing Group II and III and organic peroxides...

  9. 49 CFR 173.152 - Exceptions for Division 5.1 (oxidizers) and Division 5.2 (organic peroxides).

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Division 5.2 (organic peroxides). 173.152 Section 173.152 Transportation Other Regulations Relating to... Exceptions for Division 5.1 (oxidizers) and Division 5.2 (organic peroxides). (a) General. Exceptions for.... Limited quantities of oxidizers (Division 5.1) in Packing Group II and III and organic peroxides...

  10. Hydrogen-bis[2-(4-dimethylaminostyryl)-quinoline-1-oxide]dichlorocuprate (I) from X-ray study

    NASA Astrophysics Data System (ADS)

    Ekimova, T. A.; Tafeenko, V. A.; Aleshina, L. A.; Basalaev, R. S.; Andreev, V. P.; Nizhnik, Ya. P.

    2013-03-01

    X-ray diffraction data on powder and single-crystal samples were used to determine the crystal structure of hydrogen-bis[2-(4-dimethylaminostyryl)-quinoline-1-oxide]dichlorocuprate (I): monoclinic system, sp. gr. P21/ n, and Z = 2. Two molecules of N oxide of 2-(4-dimethylaminostyryl)quinoline are bound through a hydrogen atom located at the center of symmetry, thus forming a complex cation.

  11. Hydrogen-bis[2-(4-dimethylaminostyryl)-quinoline-1-oxide]dichlorocuprate (I) from X-ray study

    SciTech Connect

    Ekimova, T. A.; Tafeenko, V. A.; Aleshina, L. A.; Basalaev, R. S.; Andreev, V. P.; Nizhnik, Ya. P.

    2013-03-15

    X-ray diffraction data on powder and single-crystal samples were used to determine the crystal structure of hydrogen-bis[2-(4-dimethylaminostyryl)-quinoline-1-oxide]dichlorocuprate (I): monoclinic system, sp. gr. P2{sub 1}/n, and Z = 2. Two molecules of N oxide of 2-(4-dimethylaminostyryl)quinoline are bound through a hydrogen atom located at the center of symmetry, thus forming a complex cation.

  12. Regio- and Stereoselective Synthesis of Sulfur-Bearing Four-Membered Heterocycles: Direct Access to 2,4-Disubstituted Thietane 1-Oxides.

    PubMed

    Degennaro, Leonardo; Carroccia, Laura; Parisi, Giovanna; Zenzola, Marina; Romanazzi, Giuseppe; Fanelli, Flavio; Pisano, Luisa; Luisi, Renzo

    2015-12-18

    Starting from readily available C2-substituted thietane 1-oxides, a straightforward synthesis of new C2,C4-disubstituted thietane 1-oxides has been developed by using a lithiation/electrophilic trapping sequence. The chemical and configurational stability of lithiated C2-substituted thietane 1-oxides has been investigated as well as the stereochemical implications for this process. The results demonstrate that a stereoselective functionalization at the C2, C4 positions of a thietane is feasible, leaving intact the four-membered ring. PMID:26566011

  13. Mutagenesis of the C1 Oxidation Pathway in Methanosarcina barkeri: New Insights into the Mtr/Mer Bypass Pathway▿

    PubMed Central

    Welander, Paula V.; Metcalf, William W.

    2008-01-01

    A series of Methanosarcina barkeri mutants lacking the genes encoding the enzymes involved in the C1 oxidation/reduction pathway were constructed. Mutants lacking the methyl-tetrahydromethanopterin (H4MPT):coenzyme M (CoM) methyltransferase-encoding operon (Δmtr), the methylene-H4MPT reductase-encoding gene (Δmer), the methylene-H4MPT dehydrogenase-encoding gene (Δmtd), and the formyl-methanofuran:H4MPT formyl-transferase-encoding gene (Δftr) all failed to grow using either methanol or H2/CO2 as a growth substrate, indicating that there is an absolute requirement for the C1 oxidation/reduction pathway for hydrogenotrophic and methylotrophic methanogenesis. The mutants also failed to grow on acetate, and we suggest that this was due to an inability to generate the reducing equivalents needed for biosynthetic reactions. Despite their lack of growth on methanol, the Δmtr and Δmer mutants were capable of producing methane from this substrate, whereas the Δmtd and Δftr mutants were not. Thus, there is an Mtr/Mer bypass pathway that allows oxidation of methanol to the level of methylene-H4MPT in M. barkeri. The data further suggested that formaldehyde may be an intermediate in this bypass; however, no methanol dehydrogenase activity was found in Δmtr cell extracts, nor was there an obligate role for the formaldehyde-activating enzyme (Fae), which has been shown to catalyze the condensation of formaldehyde and H4MPT in vitro. Both the Δmer and Δmtr mutants were able to grow on a combination of methanol plus acetate, but they did so by metabolic pathways that are clearly distinct from each other and from previously characterized methanogenic pathways. PMID:18178739

  14. Study of the DNA Damage Checkpoint using Xenopus Egg Extracts

    PubMed Central

    Patel, Yogin; Gowda, Vrushab; Yan, Shan

    2012-01-01

    On a daily basis, cells are subjected to a variety of endogenous and environmental insults. To combat these insults, cells have evolved DNA damage checkpoint signaling as a surveillance mechanism to sense DNA damage and direct cellular responses to DNA damage. There are several groups of proteins called sensors, transducers and effectors involved in DNA damage checkpoint signaling (Figure 1). In this complex signaling pathway, ATR (ATM and Rad3-related) is one of the major kinases that can respond to DNA damage and replication stress. Activated ATR can phosphorylate its downstream substrates such as Chk1 (Checkpoint kinase 1). Consequently, phosphorylated and activated Chk1 leads to many downstream effects in the DNA damage checkpoint including cell cycle arrest, transcription activation, DNA damage repair, and apoptosis or senescence (Figure 1). When DNA is damaged, failing to activate the DNA damage checkpoint results in unrepaired damage and, subsequently, genomic instability. The study of the DNA damage checkpoint will elucidate how cells maintain genomic integrity and provide a better understanding of how human diseases, such as cancer, develop. Xenopus laevis egg extracts are emerging as a powerful cell-free extract model system in DNA damage checkpoint research. Low-speed extract (LSE) was initially described by the Masui group1. The addition of demembranated sperm chromatin to LSE results in nuclei formation where DNA is replicated in a semiconservative fashion once per cell cycle. The ATR/Chk1-mediated checkpoint signaling pathway is triggered by DNA damage or replication stress 2. Two methods are currently used to induce the DNA damage checkpoint: DNA damaging approaches and DNA damage-mimicking structures 3. DNA damage can be induced by ultraviolet (UV) irradiation, γ-irradiation, methyl methanesulfonate (MMS), mitomycin C (MMC), 4-nitroquinoline-1-oxide (4-NQO), or aphidicolin3, 4. MMS is an alkylating agent that inhibits DNA replication and activates

  15. The vibrational spectra of 1,3-dithiane-1-oxide and 1,3-dithia-1-oxocyclohept-5-ene

    NASA Astrophysics Data System (ADS)

    Noskov, A. I.; Fishman, A. I.; Galjautdinova, A. N.; Klimovitskii, E. N.

    2010-09-01

    The IR spectra of 1,3-dithiane-1-oxide (I) and 1,3-dithia-1-oxocyclohept-5-ene (II) were recorded in solution, solid and liquid phase over 4000-400 cm -1 spectral range. It was found that both (I) and (II) in liquid phase and solutions exist in two conformations: (I) chair-e ( Ce) and chair-a ( Ca) with equatorial and axial positions of the S dbnd O bond, respectively, and (II) chair-e ( Ce) and boat-e ( Be). The intensity variations with temperature (300-180 K) of the bands 632 ( Ca) and 644 cm -1 ( Ce) of (I) in acetone-d 6 and the bands 482 ( Be) и 448 cm -1 ( Ce) of (II) in melt were employed in Van't Hoff plot and gave the values Δ H°( Ca - Ce) = 380 ± 40 cal mol -1 (I) and Δ H° ( Be - Ce) = 400 ± 100 cal mol -1 (II). Ab initio calculations were carried out with the Gaussian 98 program using the basis set 6-31G(d) for (I) and 6-311++G(d,p) for (II). The energy difference between Ca and Ce conformations for (I) and Be and Ce for (II) are in a good agreement with experimental results. Vibrational frequencies for both conformations (I) and (II) were calculated. After appropriate scaling a reasonably good agreement between the experimental and calculated wave numbers was obtained.

  16. Thermochemistry of 1,3-dithiacyclohexane 1-oxide (1,3-dithiane sulfoxide): calorimetric and computational study.

    PubMed

    Roux, María Victoria; Temprado, Manuel; Jiménez, Pilar; Dávalos, Juan Z; Notario, Rafael; Martín-Valcárcel, Gloria; Garrido, Leoncio; Guzmán-Mejía, Ramón; Juaristi, Eusebio

    2004-08-01

    The enthalpies of combustion and sublimation of 1,3-dithiacyclohexane 1-oxide (1,3-dithiane sulfoxide, 2) were measured by a rotating-bomb combustion calorimeter and the Knudsen effusion technique, and the gas-phase enthalpy of formation was determined, DeltafH degrees m(g) = -98.0 +/- 1.9 kJ mol(-1). This value is not as large (negative) as could have been expected from comparison with thermochemical data available for the thiane/thiane oxide reference system. High-level ab initio molecular orbital calculations at the MP2(FULL)/6-31G(3df,2p) level were performed, and the optimized molecular and electronic structures of 2 afforded valuable information on (1) the relative conformational energies of 2-axial and 2-equatorial--the latter being 7.1 kJ mol(-1) more stable than 2-axial, (2) the possible involvement of nS --> sigma*(C-S(O)) hyperconjugation in 2-equatorial, (3) the lack of computational evidence for sigma(S-C) --> sigma*(S-O) stereoelectronic interaction in 2-equatorial, and (4) the relevance of a repulsive electrostatic interaction between sulfur atoms in 1,3-dithiane sulfoxide, which apparently counterbalances any nS --> sigma*(C-S(O)) stabilizing hyperconjugative interaction and accounts for the lower than expected enthalpy of formation for sulfoxide 2. PMID:15287796

  17. Characterization of poly(4-vinylpyridine 1-oxide) by free-solution capillary electrophoresis and micellar electrokinetic chromatography.

    PubMed

    Beneito-Cambra, Miriam; Herrero-Martínez, José M; Ramis-Ramos, Guillermo

    2008-08-01

    The migration characteristics of poly(4-vinylpyridine 1-oxide) (PVP-NO) in phosphate buffers of acidic pH (20 mM H3PO4 or NaH2PO4) have been studied using both free-solution capillary electrophoresis (FSCE) and MEKC. To inhibit adsorption, 250 mM o-phosphoethanolamine (2-aminoethyl dihydrogen phosphate) was used. In FSCE, PVP-NO showed a narrow peak and a broader band, both having anionic behavior. These peak and band were attributed to the free and aggregated or micellized PVP-NO forms, respectively. According to surface tension measurements, the CMC of SDS in the BGE was 1.8 and 0.48 mM in the absence and in the presence of 1000 microg/mL PVP-NO, respectively, and the association of the polymer with SDS was completed at 9.7 mM SDS. Using MEKC, a narrow peak and a broader band also appeared at SDS concentrations of ca. 1 mM, and their intensity increased with the SDS concentration. These peak and band were attributed to the formation of mixed micelles constituted by both free PVP-NO/SDS and aggregated PVP-NO/SDS, respectively. The determination of PVP-NO by FSCE in commercial additives for laundry was demonstrated.

  18. Characterization of 2,6-Diamino-3,5-Dinitropyrazine-1-Oxide (LLM-105) as an Insensitive High Explosive Material

    SciTech Connect

    Tran, T D; Pagoria, P F; Hoffman, D M; Cutting, J L; Lee, R S; Simpson, R L

    2002-04-09

    LLM-105 (2,6-diamino-3,5-dinitropyrazine-1-oxide) is a new molecule which has performance and insensitivity between those of HMX and TATB. Its calculated energy content is about 85% that of HMX and 15% more than that of TATB. It is thermally stable, insensitive to shock, spark and friction and has impact insensitivity level approaching that of TATB. These combined properties make it a realistic high-performance IHE material, attractive for applications that require moderate performance and insensitivity. Several morphologies of LLM-105 and plastic-bonded formulations containing these materials and another binder were prepared and characterized. Their physical properties and detonation spreading characteristics are compared to those of ultrafine TATB. The impact sensitivity (drop hammer results) is sensitive to particle morphologies. Detonation-spreading, spot-size tests on LLM-105 compositions showed higher energy output and superior divergence behavior than is observed for ultrafine TATB. The small-scale safety data, pressing characteristics and results from divergence experiments will be summarized.

  19. Evaluation of chemicals requiring metabolic activation in the EpiDerm™ 3D human reconstructed skin micronucleus (RSMN) assay.

    PubMed

    Aardema, Marilyn J; Barnett, Brenda B; Mun, Greg C; Dahl, Erica L; Curren, Rodger D; Hewitt, Nicola J; Pfuhler, Stefan

    2013-01-20

    The in vitro human reconstructed skin micronucleus (RSMN) assay in EpiDerm™ is a promising new assay for evaluating genotoxicity of dermally applied chemicals. A global pre-validation project sponsored by the European Cosmetics Association (Cosmetics Europe - formerly known as COLIPA), and the European Center for Validation of Alternative Methods (ECVAM), is underway. Results to date demonstrate international inter-laboratory and inter-experimental reproducibility of the assay for chemicals that do not require metabolism [Aardema et al., Mutat. Res. 701 (2010) 123-131]. We have expanded these studies to investigate chemicals that do require metabolic activation: 4-nitroquinoline-N-oxide (4NQO), cyclophosphamide (CP), dimethylbenzanthracene (DMBA), dimethylnitrosamine (DMN), dibenzanthracene (DBA) and benzo(a)pyrene (BaP). In this study, the standard protocol of two applications over 48h was compared with an extended protocol involving three applications over 72h. Extending the treatment period to 72h changed the result significantly only for 4NQO, which was negative in the standard 48h dosing regimen, but positive with the 72h treatment. DMBA and CP were positive in the standard 48h assay (CP induced a more reproducible response with the 72h treatment) and BaP gave mixed results; DBA and DMN were negative in both the 48h and the 72h dosing regimens. While further work with chemicals that require metabolism is needed, it appears that the RMSN assay detects some chemicals that require metabolic activation (4 out of 6 chemicals were positive in one or both protocols). At this point in time, for general testing, the use of a longer treatment period in situations where the standard 48h treatment is negative or questionable is recommended.

  20. Bioactivity of pyridine-2-thiolato-1-oxide metal complexes: Bi(III), Fe(III) and Ga(III) complexes as potent anti-Mycobacterium tuberculosis prospective agents.

    PubMed

    Machado, Ignacio; Marino, Leonardo Biancolino; Demoro, Bruno; Echeverría, Gustavo A; Piro, Oscar E; Leite, Clarice Q F; Pavan, Fernando R; Gambino, Dinorah

    2014-11-24

    In the search for new therapeutic tools against tuberculosis and to further address the therapeutic potential of pyridine-2-thiol 1-oxide (Hmpo) metal complexes, two new octahedral [M(III)(mpo)3] complexes, with M = Ga or Bi, were synthesized and characterized in the solid state and in solution. Attempts to crystallize [Ga(III)(mpo)3] in CH2Cl2 led to single crystals of the reaction product [GaCl(mpo)2], where the gallium(III) ion is in a square basis pyramidal environment, trans-coordinated at the basis to two pyridine-2-thiolato 1-oxide anions acting as bidentate ligands through their oxygen and sulfur atoms. The biological activity of the new [M(III)(mpo)3] complexes together with that of the previously reported Fe(III) analogous compound and the pyridine-2-thiol 1-oxide sodium salt (Na mpo) was evaluated on Mycobacterium tuberculosis. The compounds showed excellent activity, both in the standard strain H37Rv ATCC 27294 (pan-susceptible) and in five clinical isolates that are resistant to the standard first-line anti-tuberculosis drugs isoniazid and rifampicin. These pyridine-2-thiol 1-oxide derivatives are promising compounds for the treatment of resistant tuberculosis.

  1. MEASUREMENT OF HYDROXYL RADICAL ACTIVITY IN A SOIL SLURRY USING THE SPIN TRAP A-(4-PYRIDYL-1-OXIDE)-N-TERT-BUTYLNITRONE

    EPA Science Inventory

    The spin trap compound a-(4-pyridyl-1-oxide)N-tert-butylnitrone (4-POBN) served as a probe to estimate the activity of Fenton-derived hydroxyl radicals (.OH) in a batch suspension comprised of silica sand and crushes goethite ore. The rate of probe disappearance was used to anal...

  2. Bioactivity of pyridine-2-thiolato-1-oxide metal complexes: Bi(III), Fe(III) and Ga(III) complexes as potent anti-Mycobacterium tuberculosis prospective agents.

    PubMed

    Machado, Ignacio; Marino, Leonardo Biancolino; Demoro, Bruno; Echeverría, Gustavo A; Piro, Oscar E; Leite, Clarice Q F; Pavan, Fernando R; Gambino, Dinorah

    2014-11-24

    In the search for new therapeutic tools against tuberculosis and to further address the therapeutic potential of pyridine-2-thiol 1-oxide (Hmpo) metal complexes, two new octahedral [M(III)(mpo)3] complexes, with M = Ga or Bi, were synthesized and characterized in the solid state and in solution. Attempts to crystallize [Ga(III)(mpo)3] in CH2Cl2 led to single crystals of the reaction product [GaCl(mpo)2], where the gallium(III) ion is in a square basis pyramidal environment, trans-coordinated at the basis to two pyridine-2-thiolato 1-oxide anions acting as bidentate ligands through their oxygen and sulfur atoms. The biological activity of the new [M(III)(mpo)3] complexes together with that of the previously reported Fe(III) analogous compound and the pyridine-2-thiol 1-oxide sodium salt (Na mpo) was evaluated on Mycobacterium tuberculosis. The compounds showed excellent activity, both in the standard strain H37Rv ATCC 27294 (pan-susceptible) and in five clinical isolates that are resistant to the standard first-line anti-tuberculosis drugs isoniazid and rifampicin. These pyridine-2-thiol 1-oxide derivatives are promising compounds for the treatment of resistant tuberculosis. PMID:25261824

  3. An RNA synthesis inhibition assay for detecting toxic substances using click chemistry.

    PubMed

    Kametani, Yukiko; Iwai, Shigenori; Kuraoka, Isao

    2014-04-01

    Biological risk assessment studies of chemical substances that induce DNA lesions have been primarily based on the action of DNA polymerases during replication. However, DNA lesions interfere not only with replication, but also with transcription. There is no simple method for the detection of the DNA lesion-induced inhibition of transcription. Here, we report an assay for estimating the toxicity of chemical substances by visualizing transcription in mammalian cells using nucleotide analog 5-ethynyluridine (EU) and its click chemistry reaction. Ultraviolet light and representative chemical substances (camptothecin, 4-nitroquinoline-1-oxide, mitomycin C, and cisplatin, but not etoposide) of DNA- damaging agents show toxicity, as indicated by RNA synthesis inhibition in response to DNA damage in HeLa cells. Using titanium dioxide, we observed RNA synthesis inhibition in response to the rutile form, but not the anatase form, indicating that rutile titanium dioxide is a toxic substance. Because this method is based on the transcriptional response to DNA lesions, we can use terminally differentiated neuron-like PC12 cells, the differentiation of which can be induced by nerve growth factors, for evaluating chemical substances. Ultraviolet light and some chemicals (camptothecin, 4-nitroquinoline-1-oxide, mitomycin C, and cisplatin, but not etoposide) inhibited RNA synthesis in non-differentiated PC12 cells. Conversely, camptothecin and cisplatin did not inhibit RNA synthesis in differentiated PC12 cells, but 4-nitroquinoline-1-oxide, mitomycin C, and etoposide did. And using titanium dioxide, we did not observed any RNA synthesis inhibition. These data suggest that this method might be used to estimate the potential risk of chemical substances in differentiated mammalian cells, which are the most common cell type found in the human body.

  4. Catabolism of (2E)-4-Hydroxy-2-nonenal via ω- and ω-1-Oxidation Stimulated by Ketogenic Diet*

    PubMed Central

    Jin, Zhicheng; Berthiaume, Jessica M.; Li, Qingling; Henry, Fabrice; Huang, Zhong; Sadhukhan, Sushabhan; Gao, Peng; Tochtrop, Gregory P.; Puchowicz, Michelle A.; Zhang, Guo-Fang

    2014-01-01

    Oxidative stress triggers the peroxidation of ω-6-polyunsaturated fatty acids to reactive lipid fragments, including (2E)-4-hydroxy-2-nonenal (HNE). We previously reported two parallel catabolic pathways of HNE. In this study, we report a novel metabolite that accumulates in rat liver perfused with HNE or 4-hydroxynonanoic acid (HNA), identified as 3-(5-oxotetrahydro-2-furanyl)propanoyl-CoA. In experiments using a combination of isotopic analysis and metabolomics studies, three catabolic pathways of HNE were delineated following HNE conversion to HNA. (i) HNA is ω-hydroxylated to 4,9-dihydroxynonanoic acid, which is subsequently oxidized to 4-hydroxynonanedioic acid. This is followed by the degradation of 4-hydroxynonanedioic acid via β-oxidation originating from C-9 of HNA breaking down to 4-hydroxynonanedioyl-CoA, 4-hydroxyheptanedioyl-CoA, or its lactone, 2-hydroxyglutaryl-CoA, and 2-ketoglutaric acid entering the citric acid cycle. (ii) ω-1-hydroxylation of HNA leads to 4,8-dihydroxynonanoic acid (4,8-DHNA), which is subsequently catabolized via two parallel pathways we previously reported. In catabolic pathway A, 4,8-DHNA is catabolized to 4-phospho-8-hydroxynonanoyl-CoA, 3,8-dihydroxynonanoyl-CoA, 6-hydroxyheptanoyl-CoA, 4-hydroxypentanoyl-CoA, propionyl-CoA, and acetyl-CoA. (iii) The catabolic pathway B of 4,8-DHNA leads to 2,6-dihydroxyheptanoyl-CoA, 5-hydroxyhexanoyl-CoA, 3-hydroxybutyryl-CoA, and acetyl-CoA. Both in vivo and in vitro experiments showed that HNE can be catabolically disposed via ω- and ω-1-oxidation in rat liver and kidney, with little activity in brain and heart. Dietary experiments showed that ω- and ω-1-hydroxylation of HNA in rat liver were dramatically up-regulated by a ketogenic diet, which lowered HNE basal level. HET0016 inhibition and mRNA expression level suggested that the cytochrome P450 4A are main enzymes responsible for the NADPH-dependent ω- and ω-1-hydroxylation of HNA/HNE. PMID:25274632

  5. Induction of mutagenesis and transformation in BALB/c-3T3 clone A31-1 cells by diverse chemical carcinogens

    SciTech Connect

    Lubet, R.A. ); Kouri, R.E.; Curren, R.A.; Putman, D.L.; Schechtman, L.M. )

    1990-01-01

    BALB/c-3T3 cells were employed to examine the genotoxic potential of a variety of known chemical carcinogens. BALB/c-3T3 cells displayed a dose-dependent transformation response to a variety of carcinogens (polycyclic hydrocarbons, methylating agents, ethylating agents, aflatoxin B{sub 1} (AFT{sub 1}), and 4-nitroquinoline-N-oxide (4-NQO)). When the ability of these compounds to induce mutagenesis to resistance to the cardiac glycoside ouabain (OUA{sup R}) was examined, the authors found the short chain alkylating agents to be particularly effective mutagens, causing biologic effects at doses below those necessary to induce a transformation response. In contrast, the polycyclic hydrocarbons which were potent transforming agents were weaker, albeit significant, mutagens for the OUA{sup R} locus in this system, while AFB{sub 1} was quite weak. Further studies were performed with 5-azacytidine (5-AZA) and the nongenotoxic carcinogen cinnamyl anthranilate (CIN). 5-AZA was a potent transforming agent, but failed to cause mutagenesis. CIN similarly caused in vitro transformation. When a series of eight structurally diverse compounds were examined in both the BALB/c-3T3 and C3H10T1/2 mouse fibroblast transformation systems, the BALB/c-3T3 system was shown to be sensitive to a wide variety of potential carcinogens, whereas the C3H10T1/2 system proved routinely sensitive only to the polycyclic hydrocarbons.

  6. Genetic characterization of cells of homocystinuria patients with disrupted DNA repair system

    SciTech Connect

    Sinel'shchikova, T.A.; L'vova, G.N.; Shoniya, N.N.; Zasukhina, G.D.

    1986-08-01

    Fibroblasts obtained from biopsy material and lymphocytes of patients with homocystinuria were investigated for repair activity according to the following criteria: rejoined DNA breaks, induced by 4-nitroquinoline-1-oxide and ..gamma..-radiation; indices of reactivation and induced mutagenesis of smallpox vaccine virus treated with these mutagens. In lymphocytes a defect of DNA repair was observed according to all criteria investigated. During passage of fibroblast cultures, inhibition of repair activity of cells was preserved according to ..gamma..-type. Increase in the number of spontaneous and ..gamma..-induced mutations of virus was noted according to degree of passage of fibroblasts.

  7. Enhancement of the mutagenicity of amino acid pyrolysates by phthalate esters.

    PubMed

    Sato, T; Nagase, H; Sato, K; Niikawa, M; Kito, H

    1994-01-01

    The ability of phthalic acid, phthalic acid anhydride, and various phthalate esters to enhance the mutagenicity of many amino acid pyrolysates was observed with the Ames test (Salmonella typhimurium TA98), but not the SOS Chromotest. Phthalate enhancement of the mutagenicity of 4-nitroquinoline-1-oxide, 2-nitrofluorene, and benzo[a]pyrene was not observed with either test. The mutagenicity-enhancing ability may be related to the induction of enzymes such as P450IIB, that metabolize amino acid pyrolysates. By quantitative structure activity relationship (QSAR) analysis, a good correlation was observed between the mutagenicity-enhancing activity of phthalates and their octanol-water partition coefficients. PMID:7851345

  8. Inorganic and organic structures as interleavers among [bis(1-methyl-3-(p-carboxylatephenyl)triazenide 1-oxide)Ni(II)] complexes to form supramolecular arrangements

    NASA Astrophysics Data System (ADS)

    Santos, Aline Joana Rolina Wohlmuth Alves; dos Santos Hackbart, Helen Cristina; Giacomini, Gabriela Xavier; Bersch, Patrícia; Paraginski, Gustavo Luiz; Hörner, Manfredo

    2016-12-01

    Alternative compounds to capture metal ions are triazenes 1-oxide since they are basic compounds O(N) with negative charge in the deprotonated form. The proximity of both coordination sites (O and N) enables these compounds to have good chelating ability and a tendency to stabilize in the formation of rings with soft and hard transition metal ions. The structure analysis by single crystal X-ray diffraction of compounds (1) and (2) demonstrate the formation of 3D supramolecular arrangements through ion-ion, ion-dipolo and dipolo-dipolo interactions. In one of them, there are [(H2O)2(CH3CH3SO)K2]2+ as linkers of polymerization and, in another complex, there are [(H2O)(CH3CH3SO)Ni(H2O)6]2+ as a linker of polymerization. These linkers act in the polymerization of the novel mononuclear complex [bis(1-methyl (p-carboxylatephenyl) triazenide 1-oxide) NiII] (3). The crystallography analysis of (1) and (2) showed distorted quadratic geometry for Ni (II), thus, there are two axial positions available in Ni (II) to be used in catalysis studies and as sensor or biosensor. In addition, this study shows the support of this novel mononuclear complex of Ni (II) (3) on protonated chitosan chains (4). The compounds (3) and (4) were characterized by spectroscopic analysis, infrared (IR) and energy dispersive X-ray detector (EDS), and by differential scanning calorimetry analysis (DSC). The specificity of ligand 1-methyl (p-carboxyphenyl) triazene 1-oxide to capture potassium and nickel ions will be tested at different pH values, as well as the capacity of the triazenide 1-oxide of Ni (II) complex, supported on chitosan polymer, or not, to act as a catalyst for organic reactions and biomimetic organic reactions.

  9. Interaction of RecA protein with pBR322 DNA modified by N-hydroxy-2-acetylaminofluorene and 4-hydroxyaminoquinoline 1-oxide.

    PubMed Central

    Kojima, M; Suzuki, M; Morita, T; Ogawa, T; Ogawa, H; Tada, M

    1990-01-01

    Interaction of RecA protein of Escherichia coli with pBR322 DNA modified by N-hydroxy-2-acetylaminofluorene (N-OH-AAF) and 4-hydroxyaminoquinoline 1-oxide (4HAQO) was investigated. RecA protein bound more efficiently to modified DNA than to unmodified DNA as judged by filter-binding and gel electrophoresis assay. The binding of RecA protein with modified DNA resulted in the stimulation of ATPase activity and the activation for RecA protein to stimulate the repressor cleavage. These abilities of RecA protein were increased proportionally to the number of adducts in the plasmid DNA (0-5 adducts). Apurinic and alkylated DNA did not activate RecA protein. We suggest that modification of DNA by N-OH-AAF and 4HAQO provides binding sites for RecA protein and may act as an activation signal for SOS response. Images PMID:2140154

  10. The Temperature-Dependent Thermal Expansion of 2,6-Diamino-3,5-dinitropyrazine-1-oxide Effected by Hydrogen Bond Network Relaxation

    NASA Astrophysics Data System (ADS)

    Li, Jingyou; Zhang, Haobin; Wen, Maoping; Xu, Jinjiang; Liu, Xiaofeng; Sun, Jie

    2016-04-01

    The temperature-dependent thermal expansion of 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105) was investigated by using powder X-ray diffraction (PXRD) together with Rietveld refinement to estimate the dimension at a crystal lattice level. In the temperature range of 30-200°C, the coefficient of thermal expansion (CTE) of LLM-105 is temperature dependent, which is different from other explosives, such as hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), 2,2‧,4,4‧,6,6‧-hexanitrostilbene (HNS) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), with constant CTEs. The results of temperature-dependent infrared (IR) spectra indicated that the intermolecular hydrogen bond network relaxes with increasing temperature, which results in temperature-dependent thermal expansion. In this work, more accurate CTEs for LLM-105 crystals are obtained and the effects of the hydrogen bond network on the thermal expansion are further clarified. These results are beneficial to the design of materials with structural peculiarities and as-expected thermal expansion to satisfy different application requirements.

  11. Mutations affecting sensitivity of the cellular slime mold Dictyostelium discoideum to DNA-damaging agents.

    PubMed

    Bronner, C E; Welker, D L; Deering, R A

    1992-09-01

    We describe 22 new mutants of D. discoideum that are sensitive to DNA damage. These mutants were isolated on the basis of sensitivity to either temperature, gamma-rays, or 4-nitroquinolone-1-oxide (4NQO). The doses of gamma-rays, ultraviolet light (UV), and 4NQO required to reduce the survival of colony-forming ability of these mutants to 10% (D10) range from 2% to 100% of the D10s for the nonmutant, parent strains. For most of the mutants, those which are very sensitive to one agent are very sensitive to all agents tested and those which are moderately sensitive to one agent, are moderately sensitive to all agents tested. One mutant is sensitive only to 4NQO. Linkage relationships have been examined for 13 of these mutants. This linkage information was used to design complementation tests to determine allelism with previously characterized complementation groups affecting sensitivity to radiation. 4 of the new mutants fall within previously identified complementation groups and 3 new complementation groups have been identified (radJ, radK and radL). Other new loci probably also exist among these new mutants. This brings the number of characterized mutants of D. discoideum which are sensitive to DNA-damaging agents to 33 and the number of assigned complementation groups to 11. PMID:1380652

  12. First-principles high-pressure unreacted equation of state and heat of formation of crystal 2,6-diamino-3, 5-dinitropyrazine-1-oxide (LLM-105)

    SciTech Connect

    Manaa, M. Riad Kuo, I-Feng W.; Fried, Laurence E.

    2014-08-14

    We report dispersion-corrected density functional theoretical calculations of the unreacted equation of state (EOS) of crystal 2,6-diamino-3, 5-dinitropyrazine-1-oxide (LLM-105) under hydrostatic compression of up to 45 GPa. Convergence tests for k-points sampling in the Brillouin zone show that a 3 × 1 × 2 mesh is required to reproduce the X-ray crystal structure at ambient conditions, and we confirm our finding with a separate supercell calculation. Our high-pressure EOS yields a bulk modulus of 19.2 GPa, and indicates a tendency towards anisotropic compression along the b lattice vector due to molecular orientations within the lattice. We find that the electronic energy band gap decreases from a semiconductor type of 1.3 eV at 0 GPa to quasi-metallic type of 0.6 eV at 45 GPa. The extensive intermolecular hydrogen bonds involving the oxide (–NO) and dioxide (–NO{sub 2}) interactions with the amine (–NH{sub 2}) group showed enhanced interactions with increasing pressure that should be discernible in the mid IR spectral region. We do not find evidence for structural phase transitions or chemically induced transformations within the pressure range of our study. The gas phase heat of formation is calculated at the G4 level of theory to be 22.48 kcal/mol, while we obtain 25.92 kcal/mol using the ccCA-PS3 method. Density functional theory calculations of the crystal and the gas phases provided an estimate for the heat of sublimation of 32.4 kcal/mol. We thus determine the room-temperature solid heat of formation of LLM-105 to be −9.9 or −6.5 kcal/mol based on the G4 or ccCA-PS3 methods, respectively.

  13. Malignant conversion and metastasis of mouse skin tumors: a comparison of SENCAR and CD-1 mice

    SciTech Connect

    Hennings, H.; Spangler, E.F.; Shores, R.; Mitchell, P.; Devor, D.; Shamsuddin, A.K.M.; Elgjo, K.M.; Yuspa, S.H.

    1986-09-01

    The progression of papillomas to squamous cell carcinomas (malignant conversion) was studied in the skin of SENCAR and Charles River CD-1 mice, using a three-stage treatment protocol. After initiation with 7,12-dimethylbenz(a)anthracene (DMBA) (stage I) and limited promotion by 12-O-tetradecanoylphorbol-13-acetate (TPA) (stage II), papilloma-bearing mice were treated (stage III) with either tumor initiators, such as urethane, N-methyl-N'nitro-N nitrosoguanidine (MNNG) or 4-nitroquinoline-n-oxide (R-NQO), the promoter TPA, or solvent (acetone). Similar final carcinoma yields were found in the mice treated in stage III with TPA or acetone, although carcinomas developed earlier in the TPA-treated mice. In contrast, treatment with tumor initiators in stage III increased both the rate of appearance and the final yield of carcinomas. Similar results were obtained in both SENCAR and CD-1 mice. A papilloma stage appears to be necessary for carcinoma development since elimination of TPA treatment in stage II greatly reduced the incidence of both papillomas and carcinomas in both stocks of mice. The heterogeneity of papillomas with regard to progression to carcinomas is demonstrated by the low rate of conversion of TPA-dependent papillomas and the high rate of conversion of persistent papillomas in CD-1 mice. The carcinomas that develop using the three-stage regimen vary in metastatic potential. In CD-1 mice, the frequency of metastases to lymph nodes were similar in groups treated in stage III with MNNG, urethane, 4-NQO, TPA, or acetone, but treatment with urethane substantially increased metastases to the lung. In SENCAR mice, this effect of urethane was not observed, but lymph node and lung metastases appeared too be increased by stage III treatment with MNNG.

  14. A Novel ATP-Binding Cassette Transporter Involved in Multidrug Resistance in the Phytopathogenic Fungus Penicillium digitatum

    PubMed Central

    Nakaune, Ryoji; Adachi, Kiichi; Nawata, Osamu; Tomiyama, Masamitsu; Akutsu, Katsumi; Hibi, Tadaaki

    1998-01-01

    Demethylation inhibitor (DMI)-resistant strains of the plant pathogenic fungus Penicillium digitatum were shown to be simultaneously resistant to cycloheximide, 4-nitroquinoline-N-oxide (4NQO), and acriflavine. A PMR1 (Penicillium multidrug resistance) gene encoding an ATP-binding cassette (ABC) transporter (P-glycoprotein) was cloned from a genomic DNA library of a DMI-resistant strain (LC2) of Penicillium digitatum by heterologous hybridization with a DNA fragment containing an ABC-encoding region from Botrytis cinerea. Sequence analysis revealed significant amino acid homology to the primary structures of PMR1 (protein encoded by the PMR1 gene) and ABC transporters of Saccharomyces cerevisiae (PDR5 and SNQ2), Schizosaccharomyces pombe (HBA2), Candida albicans (CDR1), and Aspergillus nidulans (AtrA and AtrB). Disruption of the PMR1 gene of P. digitatum DMI-resistant strain LC2 demonstrated that PMR1 was an important determinant of resistance to DMIs. The effective concentrations inhibiting radial growth by 50% (EC50s) and the MICs of fenarimol and bitertanol for the PMR1 disruptants (Δpmr1 mutants) were equivalent to those for DMI-sensitive strains. Northern blot analysis indicated that severalfold more PMR1 transcript accumulated in the DMI-resistant strains compared with those in DMI-sensitive strains in the absence of fungicide. In both DMI-resistant and -sensitive strains, transcription of PMR1 was strongly enhanced within 10 min after treatment with the DMI fungicide triflumizole. These results suggested that the toxicant efflux system comprised of PMR1 participates directly in the DMI resistance of the fungus. PMID:9758830

  15. [Bioantimutagenic effect of the culture fluid of Streptococcus faecalis on mutagenesis induced by 2-nitrofluorene in Salmonella typhimurium TA 1538 and TA 98].

    PubMed

    Vorob'eva, L I; Cherdyntseva, T A; Abilev, S K

    1996-01-01

    Streptococcus faecalis growing in rich organic media or synthetic medium containing 0.1% trypton and 0.05% yeast extract was shown to form substances with a bioantimutagenic activity against the mutagenicity of 2-nitrofluorene and 4-nitroquinoline-1-oxide, which induce frameshift and base-pair substitution mutations, respectively. The maximum accumulation of antimutagens in the medium was observed within 16-24 h of growth. The modified Ames test showed that the culture liquid of Str. faecalis possessed a higher antimutagenic activity for Salmonella typhimurium strain TA 1538 than for strain TA 98 with an enhanced SOS response. Fractionation of the culture liquid revealed that the bioantimutagenic activity is localized in the fraction of peptides with molecular masses of less than 12 kDa. PMID:8721607

  16. Inhibitory effect of hemin on the mutagenic activities of carcinogens.

    PubMed

    Arimoto, S; Negishi, T; Hayatsu, H

    1980-11-01

    An inhibitory effect of hemin on mutagenicities of a range of carcinogens was found by adding hemin to the preincubation mixture of the Ames' test. Strong inhibitions were observed for benzo[alpha]pyrene, 3-methylcholanthrene, 7,10-dimethylbenz[alpha]anthracene, chrysene, 2-acetylaminofluorene, 2-nitrofluorene and aflatoxin B1. Generally, 50% inhibition was caused by an amount of hemin 1--2 equivalents to the mutagen. Excess of hemin caused complete inhibitions. Hemin did not affect the mutagenicities of 2-(2-furyl)-3-(5-nitro-2-furyl)acrylamide, 4-nitroquinoline-1-oxide, nitromin, N-methyl-N-nitrosourea, N-methyl-N'-nitro-N-nitrosoguanidine, N-nitrosodi-n-butyl-amine, quinoxaline-1,4-dioxide and carbadox. Biliverdin, bilirubin and chlorophyllin were also effective as inhibitors for the mutagenicity of benzo[alpha]pyrene. PMID:7226136

  17. IGF-1, oxidative stress, and atheroprotection

    PubMed Central

    Higashi, Yusuke; Sukhanov, Sergiy; Anwar, Asif; Shai, Shaw-Yung; Delafontaine, Patrice

    2009-01-01

    Atherosclerosis is a chronic inflammatory disease in which early endothelial dysfunction and subintimal modified lipoprotein deposition progress to complex, advanced lesions that are predisposed to erosion, rupture and thrombosis. Oxidative stress plays a critical role not only in initial lesion formation but also in lesion progression and destabilization. While growth factors are thought to promote vascular smooth muscle cell proliferation and migration, thereby increasing neointima, recent animal studies indicate that IGF-1 exerts pleiotropic anti-oxidant effects along with anti-inflammatory effects that together reduce atherosclerotic burden. This review discusses the effects of IGF-1 in vascular injury and atherosclerosis models, emphasizing the relationship between oxidative stress and potential atheroprotective actions of IGF-1. PMID:20071192

  18. The high pressure structure and equation of state of 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105) up to 20 GPa: X-ray diffraction measurements and first principles molecular dynamics simulations

    SciTech Connect

    Stavrou, Elissaios Riad Manaa, M. Zaug, Joseph M.; Kuo, I-Feng W.; Pagoria, Philip F.; Crowhurst, Jonathan C.; Armstrong, Michael R.; Kalkan, Bora

    2015-10-14

    Recent theoretical studies of 2,6-diamino-3,5-dinitropyrazine-1-oxide (C{sub 4}H{sub 4}N{sub 6}O{sub 5} Lawrence Livermore Molecule No. 105, LLM-105) report unreacted high pressure equations of state that include several structural phase transitions, between 8 and 50 GPa, while one published experimental study reports equation of state (EOS) data up to a pressure of 6 GPa with no observed transition. Here we report the results of a synchrotron-based X-ray diffraction study and also ambient temperature isobaric-isothermal atomistic molecular dynamics simulations of LLM-105 up to 20 GPa. We find that the ambient pressure phase remains stable up to 20 GPa; there is no indication of a pressure induced phase transition. We do find a prominent decrease in b-axis compressibility starting at approximately 13 GPa and attribute the stiffening to a critical length where inter-sheet distance becomes similar to the intermolecular distance within individual sheets. The ambient temperature isothermal equation of state was determined through refinements of measured X-ray diffraction patterns. The pressure-volume data were fit using various EOS models to yield bulk moduli with corresponding pressure derivatives. We find very good agreement between the experimental and theoretically derived EOS.

  19. The effect of various drug pretreatments on the convulsions and cerebellar cyclic nucleotide changes induced by the convulsant 4-isopropyl-2,6,7-trioxa-1-phosphatbicyclo(2,2,2)octane-1-oxide(IPTBO).

    PubMed

    Blenkinsop, I S; Coult, D B; Davies, W E; Howells, D J

    1984-01-01

    The effects of pretreatment of mice with some drugs which modify GABAergic neurotransmission on the convulsions and cerebellar cyclic nucelotide level changes induced by the subsequent intracerebroventricular administration of 4-isopropyl-2,6,7-trioxa-1-phosphabicyclo(2,2,2)octane-1-oxide (IPTBO) have been studied. Muscimol, pentobarbitone and diazepam reduced the number of animals convulsing and prolonged the time to onset of convulsions in those animals which did, whereas baclofen and ?-acetylenic GABA had no effect on the number of animals convulsing but did prolong seizure latency. All the drugs except baclofen prevented the increase in cyclic GMP concentrations following IPTBO treatment. Pentobarbitone, baclofen and ?-acetylenic GABA caused significant increases in the concentrations of cyclic AMP, whereas there was no marked effect of treatment with IPTBO alone on the levels of this nucleotide: however, IPTBO reduced the extent of the increases produced by the drugs. The results are discussed in the context of the mechanism of action of IPTBO and the involvement of GABAergic neurotransmission in convulsant and anticonvulsant activities.

  20. The high pressure structure and equation of state of 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105) up to 20 GPa: X-ray diffraction measurements and first principles molecular dynamics simulations

    DOE PAGES

    Stavou, Elissaios; Manaa, M. Riad; Zaug, Joseph M.; Kuo, I-Feng W.; Pagoria, Philip F.; Crowhurst, Jonathan C.; Armstrong, Michael R.; Kalkan, Bora

    2015-10-14

    Recent theoretical studies of 2,6-diamino-3,5-dinitropyrazine-1-oxide (C4H4N6O5 Lawrence Livermore Molecule No. 105, LLM-105) report unreacted high pressure equations of state that include several structural phase transitions, between 8 and 50 GPa, while one published experimental study reports equation of state (EOS) data up to a pressure of 6 GPa with no observed transition. Here we report the results of a synchrotron-based X-ray diffraction study and also ambient temperature isobaric-isothermal atomistic molecular dynamics simulations of LLM-105 up to 20 GPa. We find that the ambient pressure phase remains stable up to 20 GPa; there is no indication of a pressure induced phasemore » transition. We do find a prominent decrease in b-axis compressibility starting at approximately 13 GPa and attribute the stiffening to a critical length where inter-sheet distance becomes similar to the intermolecular distance within individual sheets. The ambient temperature isothermal equation of state was determined through refinements of measured X-ray diffraction patterns. The pressure-volume data were fit using various EOS models to yield bulk moduli with corresponding pressure derivatives. As a result, we find very good agreement between the experimental and theoretically derived EOS.« less

  1. The high pressure structure and equation of state of 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105) up to 20 GPa: X-ray diffraction measurements and first principles molecular dynamics simulations

    SciTech Connect

    Stavou, Elissaios; Manaa, M. Riad; Zaug, Joseph M.; Kuo, I-Feng W.; Pagoria, Philip F.; Crowhurst, Jonathan C.; Armstrong, Michael R.; Kalkan, Bora

    2015-10-14

    Recent theoretical studies of 2,6-diamino-3,5-dinitropyrazine-1-oxide (C4H4N6O5 Lawrence Livermore Molecule No. 105, LLM-105) report unreacted high pressure equations of state that include several structural phase transitions, between 8 and 50 GPa, while one published experimental study reports equation of state (EOS) data up to a pressure of 6 GPa with no observed transition. Here we report the results of a synchrotron-based X-ray diffraction study and also ambient temperature isobaric-isothermal atomistic molecular dynamics simulations of LLM-105 up to 20 GPa. We find that the ambient pressure phase remains stable up to 20 GPa; there is no indication of a pressure induced phase transition. We do find a prominent decrease in b-axis compressibility starting at approximately 13 GPa and attribute the stiffening to a critical length where inter-sheet distance becomes similar to the intermolecular distance within individual sheets. The ambient temperature isothermal equation of state was determined through refinements of measured X-ray diffraction patterns. The pressure-volume data were fit using various EOS models to yield bulk moduli with corresponding pressure derivatives. As a result, we find very good agreement between the experimental and theoretically derived EOS.

  2. Physical Characterization of RX-55-AE-5 A formulation of 97.5 % 2, 6-diamino-3, 5-dinitropyrazine-1-oxide (LLM 105) and 2.5 % Viton A

    SciTech Connect

    Weese, R K; Burnham, A K; Turner, H C; Tran, T

    2005-06-08

    With the use of modern tools such as molecular modeling on increasingly powerful computers, new materials can be evaluated by their structural activity relationships, SAR, and their approximate physical and chemical properties can be calculated in some cases with surprising accuracy. These new capabilities enable streamlined synthetic routes based on safety, performance and processing requirements, to name a few [1]. Current work includes both understanding properties of old explosives and measuring properties of new ones. The necessity to know and understand the properties of energetic materials is driven by the need to improve performance and enhance stability to various stimuli, such as thermal, friction and impact insult. This review will concentrate on the physical properties of RX-55-AE-5, which is formulated from heterocyclic explosive, 2,6-diamino-3,5-dinitropyrazine-1-oxide, LLM-105, and 2.5% Viton A. Differential scanning calorimetry, DSC, was used to measure a specific heat capacity, C{sub p}, of {approx} 0.950 J/g{center_dot} C, and a thermal conductivity, {kappa}, of {approx} 0.160 W/m{center_dot} C. The Lawrence Livermore National Laboratory (LLNL) code ''Kinetics05'' and the Advanced Kinetics and Technology Solutions (AKTS) code ''Thermokinetics'' were both used to calculate Arrhenius kinetics for decomposition of LLM-105. Both obtained an activation energy barrier E {approx} 180 kJ mol{sup -1} for mass loss in an open pan. Thermal mechanical analysis, TMA, was used to measure the coefficient of thermal expansion, CTE. The CTE for this formulation was calculated to be {approx} 61 {micro}m/m{center_dot} C. Impact, spark, friction and evolved gases are also reported.

  3. Physical Characterization of RX-55-AE-5 a Formulation of 97.5 % 2,6-Diamino-3,5-Dinitropyrazine-1-Oxide (LLM-105) and 2.5% Viton A

    SciTech Connect

    Weese, R K; Burnham, A K; Turner, H C; Tran, T D

    2005-07-28

    With the use of modern tools such as molecular modeling on increasingly powerful computers, new materials can be evaluated by their structural activity relationships, SAR, and their approximate physical and chemical properties can be calculated in some cases with surprising accuracy. These new capabilities enable streamlined synthetic routes based on safety, performance and processing requirements, to name a few [1]. Current work includes both understanding properties of old explosives and measuring properties of new ones. The necessity to know and understand the properties of energetic materials is driven by the need to improve performance and enhance stability to various stimuli, such as thermal, friction and impact insult. This review will concentrate on the physical properties of RX-55-AE-5, which is formulated from heterocyclic explosive, 2,6-diamino-3,5-dinitropyrazine-1-oxide, LLM-105, and 2.5% Viton A. Differential scanning calorimetry, DSC, was used to measure a specific heat capacity, C{sub p}, of {approx} 0.950 J/g {center_dot} C, and a thermal conductivity, {kappa}, of {approx} 0.160 W/m {center_dot} C. The Lawrence Livermore National Laboratory (LLNL) code Kinetics05 and the Advanced Kinetics and Technology Solutions (AKTS) code Thermokinetics were both used to calculate Arrhenius kinetics for decomposition of LLM-105. Both obtained an activation energy barrier E {approx} 180 kJ mol{sup -1} for mass loss in an open pan. Thermal mechanical analysis, TMA, was used to measure the coefficient of thermal expansion, CTE. The CTE for this formulation was calculated to be {approx} 61 {micro}m/m {center_dot} C. Impact, spark, friction and evolved gases are also reported.

  4. Estimates of DNA damage by the comet assay in the direct-developing frog Eleutherodactylus johnstonei (Anura, Eleutherodactylidae)

    PubMed Central

    Valencia, Laura Carolina; García, Adriana; Ramírez-Pinilla, Martha Patricia; Fuentes, Jorge Luis

    2011-01-01

    The aim of this study was to use the Comet assay to assess genetic damage in the direct-developing frog Eleutherodactylus johnstonei. A DNA diffusion assay was used to evaluate the effectiveness of alkaline, enzymatic and alkaline/enzymatic treatments for lysing E. johnstonei blood cells and to determine the amount of DNA strand breakage associated with apoptosis and necrosis. Cell sensitivity to the mutagens bleomycin (BLM) and 4-nitro-quinoline-1-oxide (4NQO) was also assessed using the Comet assay, as was the assay reproducibility. Alkaline treatment did not lyse the cytoplasmic and nuclear membranes of E. johnstonei blood cells, whereas enzymatic digestion with proteinase K (40 μg/mL) yielded naked nuclei. The contribution of apoptosis and necrosis (assessed by the DNA diffusion assay) to DNA damage was estimated to range from 0% to 8%. BLM and 4NQO induced DNA damage in E. johnstonei blood cells at different concentrations and exposure times. Dose-effect curves with both mutagens were highly reproducible and showed consistently low coefficients of variation (CV ≤ 10%). The results are discussed with regard to the potential use of the modified Comet assay for assessing the exposure of E. johnstonei to herbicides in ecotoxicological studies. PMID:22215974

  5. Ecotoxicological evaluation of caffeine and its derivatives from a simulated chlorination step.

    PubMed

    Zarrelli, Armando; Dellagreca, Marina; Iesce, Maria Rosaria; Lavorgna, Margherita; Temussi, Fabio; Schiavone, Luigi; Criscuolo, Emma; Parrella, Alfredo; Previtera, Lucio; Isidori, Marina

    2014-02-01

    Caffeine is ubiquitous in surface and ground waters and it has been proposed as a marker of the anthropogenic pressure on the environment. Sewage treatment plants based on active sludges seem to be not very efficient in its complete removal from effluents while additional disinfection treatments by chlorination are able to do it. In a simulation of the chlorination step herein we report that caffeine is transformed in six by-products: 8-chlorocaffeine, 1,3-dimethyl-5-azabarbituric acid, N,N'-dimethylparabanic acid, N,N'-dimethyloxalamide, N-methylurea and N,N'-dimethylurea. The ecotoxicity of caffeine and identified compounds was evaluated on the rotifer Brachionus calyciflorus and the alga Pseudokirchneriella subcapitata to assess acute and chronic toxicity, while SOS Chromotest and Ames Test were used to detect the genotoxic potential of the investigated compounds. Moreover, we assessed the possible antigenotoxic effect of the selected compounds using SOS Chromotest after co-incubation with the standard genotoxin, 4-nitroquinoline 1-oxide. Chronic exposure to these compounds caused inhibition of growth population on the rotifer while the algae seemed to be unaffected. Results indicated that caffeine (1), N,N'-dimethyloxamide (4) and N,N'-dimethylparabanic acid (5) reduced β-galactosidase activity in comparison with positive control, both at 1 and 5mg/L of 4-NQNO with a good dose-response.

  6. UPLC-TOF-MS Characterization and Identification of Bioactive Iridoids in Cornus mas Fruit

    PubMed Central

    West, Brett J.; Jensen, C. Jarakae

    2013-01-01

    Cornus mas L. is indigenous to Europe and parts of Asia. Although Cornus is widely considered to be an iridoid rich genera, only two iridoids have been previously found in this plant. The lack of information on taxonomically and biologically active iridoids prompted us to develop and optimize an analytical method for characterization of additional phytochemicals in C. mas fruit. An ultra performance liquid chromatography (UPLC) coupled with photodiode array spectrophotometry (PDA) and electrospray time-of-flight mass spectrometry (ESI-TOF-MS) was employed and mass parameters were optimized. Identification was made by elucidating the mass spectral data and further confirmed by comparing retention times and UV spectra of target peaks with those of reference compounds. Primary DNA damage and antigenotoxicity tests in E. coli PQ37 were used to screen the iridoids for biological activity. As a result, ten phytochemicals were identified, including iridoids loganic acid, loganin, sweroside, and cornuside. Nine of these were reported for the first time from C. mas fruit. The iridoids did not induce SOS repair of DNA, indicating a lack of genotoxic activity in E. coli PQ37. However, loganin, sweroside, and cornuside did reduce the amount of DNA damage caused by 4-nitroquinoline 1-oxide, suggesting potential antigenotoxic activity. PMID:24228188

  7. Novel protein in human epidermal keratinocytes: regulation of expression during differentiation

    SciTech Connect

    Kartasova, T.; van Muijen, G.N.; van Pelt-Heerschap, H.; van de Putte, P.

    1988-05-01

    Recently, two groups of cDNA clones have been isolated from human epidermal keratinocytes; the clones correspond to genes whose expression is stimulated by exposure of the cells to UV light or treatment with 4-nitroquinoline 1-oxide or 12-O-tetradecanoylphorbol 13-acetate. The proteins predicted by the nucleotide sequence of both groups of cDNAs are small (8 to 10 kilodaltons), are exceptionally rich in proline, glutamine, and cysteine, and contain repeating elements with a common sequence, PK PEPC. These proteins were designated sprI and sprII (small, proline rich). Here we describe the characterization of the sprIa protein, which is encoded by one of the group 1 cDNAs. The expression of this protein during keratinocyte differentiation in vitro and the distribution of the sprIa protein in some human tissues was studied by using a specific rabbit antiserum directed against a synthetic polypeptide corresponding to the 30 amino acids of the C-terminal region of the sprIa gene product. The results indicate that the expression of the sprIa protein is stimulated during keratinocyte differentiation both in vitro and in vivo.

  8. Evidence for the multistep nature of in vitro human epithelial cell carcinogenesis

    SciTech Connect

    Rhim, J.S.; Yoo, J.H.; Park, J.H.; Thraves, P.; Salehi, Z.; Dritschilo, A. )

    1990-09-01

    In keeping with the multistep development of human cancer in vivo, a stepwise approach to neoplastic transformation in vitro presents a reasonable strategy. We have recently developed an in vitro multistep model suitable for the study of human epithelial cell carcinogenesis. Upon infection with the adenovirus 12-simian virus 40 hybrid virus, primary human epidermal keratinocytes acquired an indefinite life span in culture but did not undergo malignant conversion. Subsequent addition of Kirsten murine sarcoma virus and human ras oncogene or chemical carcinogens (N-methyl-N{prime}-nitro-N-nitrosoguanidine or 4-nitroquinoline 1-oxide) to these cells induced morphological alterations and the acquisition of neoplastic properties. Subsequently it was found that this line could be transformed neoplastically by a variety of retrovirus-containing H-ras, bas, fes, fms, erbB, and src oncogenes. In addition, we found that the immortalized human epidermal keratinocyte (RHEK-1) line can be transformed neoplastically by exposure to ionizing radiation. Thus, this in vitro system may be useful in studying the interaction of a variety of carcinogenic agents and human epithelial cells. These findings demonstrate the malignant transformation of human primary epithelial cells in culture by the combined action of viruses, oncogenes, chemical carcinogens, or X-ray irradiation and support a multistep process for neoplastic conversion.

  9. Fine-mapping of DNA damage and repair in specific genomic segments.

    PubMed Central

    Govan, H L; Valles-Ayoub, Y; Braun, J

    1990-01-01

    The susceptibility of various genomic regions to DNA damage and repair is heterogeneous. While this can be related to factors such as primary sequence, physical conformation, and functional status, the exact mechanisms involved remain unclear. To more precisely define the key features of a genomic region targeted for these processes, a useful tool would be a method for fine-mapping gene-specific DNA damage and repair in vivo. Here, a polymerase chain reaction-based assay is described for measuring DNA damage and repair in small (less than 500 bp) genomic segments of three transcriptionally active but functionally distinct loci (rearranged immunoglobulin heavy chain variable region [Ig VDJ], low-density lipoprotein receptor gene, and N-ras proto-oncogene) in human tonsillar B lymphocytes. Analysis of ultraviolet (254 nm)-induced DNA damage revealed single-hit kinetics and a similar level of sensitivity (D50% approximately 6000 joule/m2) in all three regions, indicating that a single photoproduct was sufficient to fully block PCR amplification. A similar time period per unit length was required for repair of this DNA damage (average t1/2 per fragment length = 23.5 seconds per bp). DNA damage and repair was also detectable with the base adducting agent, 4-nitroquinoline-1-oxide. However, in this case IgVDJ differed from segments within the other two loci by its relative inaccessibility to alkylation. This assay thus permits high-resolution mapping of DNA damage and repair activity. Images PMID:2115669

  10. Characterization and genetic mapping of a mutation affecting apurinic endonuclease activity in Staphylococcus aureus.

    PubMed Central

    Tam, J E; Pattee, P A

    1986-01-01

    Protoplast fusion between the Rec- mutant RN981 (L. Wyman, R. V. Goering, and R. P. Novick, Genetics 76:681-702, 1974) of Staphylococcus aureus NCTC 8325 and a Rec+ NCTC 8325 derivative yielded Rec+ recombinants that exhibited the increased sensitivity to N-methyl-N'-nitro-N-nitrosoguanidine characteristic of RN981. Transformation analyses identified a specific mutation, designated ngr-374, that was responsible not only for N-methyl-N'-nitro-N-nitrosoguanidine sensitivity, but also sensitivity to methyl methanesulfonate, ethyl methanesulfonate, nitrous acid, and UV irradiation. However, ngr-374-carrying recombinants showed no significant increase in their sensitivity to mitomycin C or 4-nitroquinoline 1-oxide and were unaffected in recombination proficiency. In vitro assays showed that ngr-374-carrying strains had lower apurinic/apyrimidinic endonuclease activities than the wild type. The chromosomal locus occupied by ngr-374 was shown to exist in the gene order omega(Chr::Tn551)40-ngr-374-thrB106. PMID:2430940

  11. Werner and Bloom helicases are involved in DNA repair in a complementary fashion.

    PubMed

    Imamura, Osamu; Fujita, Kumiko; Itoh, Chie; Takeda, Shunichi; Furuichi, Yasuhiro; Matsumoto, Takehisa

    2002-01-31

    Werner syndrome (WS) is a recessive disorder characterized by premature senescence. Bloom syndrome (BS) is a recessive disorder characterized by short stature and immunodeficiency. A common characteristic of both syndromes is genomic instability leading to tumorigenesis. WRN and BLM genes causing WS and BS, encode proteins that are closely related to the RecQ helicase. We produced WRN-/-, BLM-/- and WRN(-/-)/BLM(-/-) mutants in the chicken B-cell line DT40. WRN-/- cells showed hypersensitivities to genotoxic agents, such as 4-nitroquinoline 1-oxide, camptothecin and methyl methanesulfonate. They also showed a threefold increase in targeted integration rate of exogenous DNAs, but not in sister chromatid exchange (SCE) frequency. BLM-/- cells showed hypersensitivities to the genotoxic agents as well as ultraviolet (UV) light, in addition to a 10-fold increase in targeted integration rate and an 11-fold increase in SCE frequency. In WRN(-/-)/BLM(-/-) cells, synergistically increased hypersensitivities to the genotoxic agents were observed whereas both SCE frequencies and targeted integration rates were partially diminished compared to the single mutants. Chromosomal aberrations were also synergistically increased in WRN(-/-)/BLM(-/-) cells when irradiated with UV light in late S to G(2) phases. These results suggest that both WRN and BLM may be involved in DNA repair in a complementary fashion. PMID:11840341

  12. Bloom helicase is involved in DNA surveillance in early S phase in vertebrate cells.

    PubMed

    Imamura, O; Fujita, K; Shimamoto, A; Tanabe, H; Takeda, S; Furuichi, Y; Matsumoto, T

    2001-03-01

    Bloom syndrome (BS) is a recessive human genetic disorder characterized by short stature, immunodeficiency and an elevated risk of malignancy. The gene mutated in BS, BLM, encodes a RecQ-type DNA helicase. BS cells have mutator phenotypes such as hyper-recombination, chromosome instability and an increased frequency of sister chromatid exchange (SCE). To define the primary role of BLM, we generated BLM(-/-) mutants of the chicken B-cell line DT40. In addition to characteristics of BLM(-/-) cells reported previously by the other group, they are hypersensitive to genotoxic agents such as etoposide, bleomycin and 4-nitroquinoline-1-oxide and irradiation with the short wave length of UV (UVC) light, whereas they exhibit normal sensitivity to X-ray irradiation and hydroxyurea. UVC irradiation to BLM(-/-) cells during G(1) to early S phase caused chromosomal instability such as chromatid breaks and chromosomal quadriradials, leading to eventual cell death. These results suggest that BLM is involved in surveillance of base abnormalities in genomic DNA that may be encountered by replication forks in early S phase. Such surveillance would maintain genomic stability in vertebrate cells, resulting in the prevention of cellular tumorigenesis. PMID:11313858

  13. Vital-dye-enhanced multimodal imaging of neoplastic progression in a mouse model of oral carcinogenesis

    NASA Astrophysics Data System (ADS)

    Hellebust, Anne; Rosbach, Kelsey; Wu, Jessica Keren; Nguyen, Jennifer; Gillenwater, Ann; Vigneswaran, Nadarajah; Richards-Kortum, Rebecca

    2013-12-01

    In this longitudinal study, a mouse model of 4-nitroquinoline 1-oxide chemically induced tongue carcinogenesis was used to assess the ability of optical imaging with exogenous and endogenous contrast to detect neoplastic lesions in a heterogeneous mucosal surface. Widefield autofluorescence and fluorescence images of intact 2-NBDG-stained and proflavine-stained tissues were acquired at multiple time points in the carcinogenesis process. Confocal fluorescence images of transverse fresh tissue slices from the same specimens were acquired to investigate how changes in tissue microarchitecture affect widefield fluorescence images of intact tissue. Widefield images were analyzed to develop and evaluate an algorithm to delineate areas of dysplasia and cancer. A classification algorithm for the presence of neoplasia based on the mean fluorescence intensity of 2-NBDG staining and the standard deviation of the fluorescence intensity of proflavine staining was found to separate moderate dysplasia, severe dysplasia, and cancer from non-neoplastic regions of interest with 91% sensitivity and specificity. Results suggest this combination of noninvasive optical imaging modalities can be used in vivo to discriminate non-neoplastic from neoplastic tissue in this model with the potential to translate this technology to the clinic.

  14. Comet assay analysis of repair of DNA strand breaks in normal and deficient human cells exposed to radiations and chemicals. Evidence for a repair pathway specificity of DNA ligation

    SciTech Connect

    Nocentini, S.

    1995-11-01

    The induction and resealing of DNA strand breaks in a cell line with a proven defect in DNA ligase I, 46BR, and in two Bloom`s syndrome cell lines. YBL6 and GM 1492, were compared to those observed in normal human 1BR/3 fibroblasts after treatment with a variety of genotoxic agents whose lesions are processed by different repair pathways. This analysis was performed using the single-cell gel electrophoresis assay. The three types of cells were found to have similar capabilities to recognize and incise ultraviolet photoproducts and also demonstrated similar amounts of DNA breaks immediately after {gamma} irradiation. During post-treatment incubation, 46BR cells showed a marked DNA re-ligation defect after ultraviolet radiation damage, GM 1492 cells demonstrated a highly reduced DNA joining ability after relatively high doses of ultraviolet radiation, and YBL6 cells were particularly affected in DNA re-ligation after damage by 4-nitroquinoline-1-oxide. The two Bloom`s syndrome cell lines and 46BR cells had a nearly normal ability to reseal breaks resulting from {gamma} irradiation or treatment with xanthine plus xanthine oxidase. These findings suggest that different DNA ligases may be involved in different DNA repair pathways in human cells. 60 refs., 7 figs.

  15. Isolation, characterization, and UV-stimulated expression of two families of genes encoding polypeptides of related structure in human epidermal keratinocytes

    SciTech Connect

    Kartasova, T.; Van de Putte, P.

    1988-05-01

    By screening of a cDNA library made on mRNA isolated from UV-irradiated human epidermal keratinocytes for sequences whose relative concentration increases in the cytoplasm after irradiation, the authors isolated 40 cDNA clones. Here they describe two distinct groups of cDNA clones which do not cross-hybridize to each other but nevertheless encode proteins of very similar primary structure. These polypeptides are small (8 to 10 kilodaltons) and exceptionally rich in proline, cysteine, and glutamine and have similar repeating elements not found elsewhere. The new proteins were designated sprI and sprII (small, proline rich). The presence of prolines and cysteines suggests that they may be either structural proteins with a strong secondary structure or metal-binding proteins such as metallothioneins. Southern blot and sequence analyses of the cDNAs indicate that at least the sprII group of clones represents a family of related genes. The nucleotide sequence of both groups seems to be conserved upon evolution. The level of mRNAs corresponding to the two groups of cDNAs is increased in the cytoplasm of human epidermal keratinocytes after both UV irradiation and treatment with 4-nitroquinoline 1-oxide or 12-O-tetradecanoylphorbol 13-acetate.

  16. High-Mobility Group Box 1, Oxidative Stress, and Disease

    PubMed Central

    Kang, Rui; Zeh, Herbert J.

    2011-01-01

    Abstract Oxidative stress and associated reactive oxygen species can modify lipids, proteins, carbohydrates, and nucleic acids, and induce the mitochondrial permeability transition, providing a signal leading to the induction of autophagy, apoptosis, and necrosis. High-mobility group box 1 (HMGB1) protein, a chromatin-binding nuclear protein and damage-associated molecular pattern molecule, is integral to oxidative stress and downstream apoptosis or survival. Accumulation of HMGB1 at sites of oxidative DNA damage can lead to repair of the DNA. As a redox-sensitive protein, HMGB1 contains three cysteines (Cys23, 45, and 106). In the setting of oxidative stress, it can form a Cys23-Cys45 disulfide bond; a role for oxidative homo- or heterodimerization through the Cys106 has been suggested for some of its biologic activities. HMGB1 causes activation of nicotinamide adenine dinucleotide phosphate oxidase and increased reactive oxygen species production in neutrophils. Reduced and oxidized HMGB1 have different roles in extracellular signaling and regulation of immune responses, mediated by signaling through the receptor for advanced glycation end products and/or Toll-like receptors. Antioxidants such as ethyl pyruvate, quercetin, green tea, N-acetylcysteine, and curcumin are protective in the setting of experimental infection/sepsis and injury including ischemia-reperfusion, partly through attenuating HMGB1 release and systemic accumulation. Antioxid. Redox Signal. 14, 1315–1335. PMID:20969478

  17. Abnormal regulation of DNA replication and increased lethality in ataxia telangiectasia cells exposed to carcinogenic agents

    SciTech Connect

    Jaspers, N.G.; de Wit, J.; Regulski, M.R.; Bootsma, D.

    1982-01-01

    The effect of different carcinogenic agents on the rate of semiconservative DNA replication in normal and ataxia telangiectasis (AT) cells was investigated. The rate of DNA synthesis in all AT cell strains tested was depressed to a significantly lesser extent than in normal cells after exposure to X-rays under oxia or hypoxia or to bleomycin, agents to which AT cells are hypersensitive. In contrast, inhibition of DNA replication in normal human and AT cells was similar after treatment with some DNA-methylating agents or mitomycin C. Colony-forming ability of AT cells treated with these agents was not different from normal cells. Treatment with 4-nitroquinoline 1-oxide elicited a variable response in both AT and normal cell strains. In some strains, including those shown to be hypersensitive to the drug by other workers, the inhibition of DNA synthesis was more pronounced than in other cell strains, but no significant difference between AT and normal cells could be detected. The rejoining of DNA strand breaks induced by X-rays, measured by DNA elution techniques, occurred within l2 hr after treatment and could not be correlated with the difference in DNA synthesis inhibition in AT and normal cells. After low doses of X-rays, AT cells rejoined single-strand breaks slightly more slowly than did normal cells. The rate of DNA replication in X-irradiation AT and normal cells was not affected by nicotinamide, an inhibitor of poly(adenosine diphosphate ribose) synthesis. These data indicate that the diminished inhibition of DNA replication in carcinogen-treated AT cells (a) is a general characteristic of all AT cell strains, (b) correlates with AT cellular hypersensitivity, (c) is not directly caused by the bulk of the DNA strand breaks produced by carcinogenic agents, and (d) is not based on differences in the induction of poly(adenosine diphosphate ribose) synthesis between X-irradiated AT and normal cells.

  18. Electrophile and oxidant damage of mitochondrial DNA leading to rapid evolution of homoplasmic mutations.

    PubMed

    Mambo, Elizabeth; Gao, Xiangqun; Cohen, Yoram; Guo, Zhongmin; Talalay, Paul; Sidransky, David

    2003-02-18

    mtDNA mutations occur in a wide variety of degenerative diseases and cancer. mtDNA seems to be more susceptible to DNA damage and consequently sustains higher rates of mutation than does nuclear DNA (nDNA). Many of the somatic mtDNA mutations in human cancers are located in the displacement loop (D-loop) and in particular in a polycytidine stretch (C-tract) termed D310. The D310 region exhibits polymorphic length variation among individuals and has been described as a "hot spot" for somatic mutations in many cancer types. We used real-time quantitative PCR to analyze mtDNA integrity, damage repair, and induced mutations after exposure of human adult retinal pigment epithelial (ARPE)-19 cells to 4-nitroquinoline 1-oxide, a UV-mimetic and adduct-forming carcinogen, and tert-butyl hydroperoxide, an oxidant. The mtDNA-damage profile depended on the region. Thus, the tRNA coding for glycine (tRNA(G)) was the least affected region, whereas the D-loop, and especially its D310 region, were most sensitive to damage. The time course of repair of mutations of the D-loop and especially the D310 region after exposure to DNA-damaging agents was delayed when compared with other regions and gave rise to common D310 C-tract frame-shift mutations. The induced mutations in the D310 region were predominantly homoplasmic only 7 days after exposure to damage. Our results establish that the D-loop (especially its D310 region) is highly susceptible to mutations because of its vulnerability to DNA damage and inefficient repair mechanisms. Our findings may explain the high frequency of homoplasmic D310 somatic mutations in many tumor types.

  19. DNA replication and the repair of DNA strand breaks in nuclei of Physarum polycephalum. Terminal report, August 1, 1978-March 31, 1980

    SciTech Connect

    Brewer, E.N.; Evans, T.E.

    1980-01-01

    Nuclei isolated from Physarum are able to replicate approximately 15% of the total genome in a manner which is qualitatively similar to the DNA replication process occurring in the intact organism. Such nuclei, however, are defective in the joining of Okazaki intermediates in vitro. Two DNA polymerase species, isolated from nuclei or intact plasmodia of this organism, can be separated by sucrose density gradient centrifugation. Total DNA polymerase activity is low in nuclei isolated during mitosis. A heat-stable glycoprotein material present in aqueous nuclear extracts stimulates DNA synthesis in well-washed nuclei. A sub-nuclear preparation active in DNA synthesis in vitro has been obtained from isolated nuclei of Physarum. Radiation-induced DNA double-strand breaks are rejoined in intact plasmodia and isolated nuclei of Physarum in a cell cycle-dependent manner. This phenomenon does not appear to be due to an intrinsic difference in nuclear DNA endonuclease activity at different times of the mitotic cycle. DNA strand breaks and repair induced by the carcinogen 4-nitroquinoline-1-oxide is similar in several respects to that resulting from exposure of the organism to ionizing radiation. Temperature sensitive strains of Physarum have been constructed and preliminary genetical and biochemical characterizations have been carried out. Two of the strains appear to be conditionally defective in DNA metabolism. An isogenic ploidal series of amoebae has been prepared and characterized as to uv and ionizing radiation sensitivity (in terms of cell survival). There is a direct relationship between ploidy and resistance to uv whereas ploidal change does not appear to affect the response to ionizing radiation.

  20. Suppression of Rat Oral Carcinogenesis by Agonists of Peroxisome Proliferator Activated Receptor γ

    PubMed Central

    McCormick, David L.; Horn, Thomas L.; Johnson, William D.; Peng, Xinjian; Lubet, Ronald A.; Steele, Vernon E.

    2015-01-01

    Peroxisome-proliferator-activated receptor γ (PPARγ) is a ligand-activated transcription factor that regulates cell proliferation, differentiation, and apoptosis. In vivo studies were performed to evaluate the activities of two thiazolidinedione PPARγ agonists, rosiglitazone and pioglitazone, as inhibitors of oral carcinogenesis in rats. Oral squamous cell carcinomas (OSCC) were induced in male F344 rats by 4-nitroquinoline-1-oxide (NQO; 20 ppm in the drinking water for 10 weeks). In each study, groups of 30 NQO-treated rats were exposed to a PPARγ agonist beginning at week 10 (one day after completion of NQO administration) or at week 17 (7 weeks post-NQO); chemopreventive agent exposure was continued until study termination at week 22 (rosiglitazone study) or week 24 (pioglitazone study). Administration of rosiglitazone (800 mg/kg diet) beginning at week 10 increased survival, reduced oral cancer incidence, and reduced oral cancer invasion score in comparison to dietary controls; however, chemopreventive activity was largely lost when rosiglitazone administration was delayed until week 17. Administration of pioglitazone (500 mg/kg diet beginning at week 10 or 1000 mg/kg diet beginning at week 17) induced significant reductions in oral cancer incidence without significant effects on OSCC invasion scores. Transcript levels of PPARγ and its three transcriptional variants (PPARγv1, PPARγv2, and PPARγv3) were not significantly different in OSCC versus age- and site-matched phenotypically normal oral tissues from rats treated with NQO. These data suggest that PPARγ provides a useful molecular target for oral cancer chemoprevention, and that overexpression of PPARγ at the transcriptional level in neoplastic lesions is not essential for chemopreventive efficacy. PMID:26516762

  1. Purification and characterization of 1-nitropyrene nitroreductases from Bacteroides fragilis.

    PubMed Central

    Kinouchi, T; Ohnishi, Y

    1983-01-01

    We isolated four nitroreductases from Bacteroides fragilis GAI0624 and examined their physicochemical and functional properties. Two major enzyme activities were found in the adsorbed and unadsorbed fractions from DEAE-cellulose column chromatography. The adsorbed fraction was subjected to Sephadex G-200 column chromatography, and two further activities were separated. One has high nitroreductase activity (nitroreductase I), and the other has low activity and relatively high molecular weight (nitroreductase III). The nitroreductase I fraction was subjected to hydroxylapatite and chromatofocusing column chromatography, and nitroreductase I was purified about 416-fold with a yield of 6.77%. The unadsorbed fraction from DEAE-cellulose column chromatography was subjected to Sepharose 2B and Sepharose 6B column chromatography. Two enzyme activities were obtained by the Sepharose 6B column chromatography. One has high activity (nitroreductase II), and the other has low activity (nitroreductase IV). Nitroreductase II was rechromatographed by Sepharose 6B gel filtration and purified about 178-fold with a yield of 9.65%. The four enzymes (nitroreductases I, II, III, and IV) were shown to be different by several criteria. Their molecular weights, determined by gel filtration, were 52,000, 320,000, 180,000, and 680,000, respectively. The substrate specificity, the effect on mutagenicity of mutagenic nitro compounds, of nitroreductases I, III, and IV was relatively high for 1-nitropyrene, dinitropyrenes, and 4-nitroquinoline 1-oxide, respectively, but nitroreductase II had broad specificity. Nitroreductase activity required a coenzyme; nitroreductases II, III, and IV were NADPH linked, but nitroreductase I was NADH linked. All enzyme activity was enhanced by addition of flavin mononucleotide and inhibited significantly by dicumarol, p-chloromercuribenzoic acid, o-iodosobenzoic acid, sodium azide, and Cu2+.(ABSTRACT TRUNCATED AT 250 WORDS) Images PMID:6639014

  2. Antimutagenic properties of lactic acid-cultured milk on chemical and fecal mutagens

    SciTech Connect

    Hosono, A.; Kashina, T.; Kada, T.

    1986-09-01

    The antimutagenic properties of milk cultured with Lactobacillus bulgaricus and Streptococcus thermophilus were examined using streptomycin-dependent strains of Salmonella in an in vitro assay system. The mutagens utilized for testing included 2-(2-furyl)-3-(5-nitro-2-furyl) acrylamide, 4-nitroquinoline-N-oxide, and fecal mutagenic extracts from cats, monkeys, dogs and other mammals. Both types of cultured milk exhibited antimutagenic activity on all mutagens used. Antimutagenic activities of the cultured milks with 2-(2-furyl)-3-(5-nitro-2-furyl) acrylamide and 4-nitroquinoline-N-oxide increased with incubation time but were thermolabile beyond 55/sup 0/C for 10 min.

  3. Oncogene transcription in normal human IMR-90 fibroblasts: induction by serum and tetradecanoyl phorbol acetate

    SciTech Connect

    Bower, E.A.; Kaji, H.

    1988-01-01

    The authors report studies of oncogene transcription induced by the addition of serum to quiescent cultures of human IMR-90 fibroblasts. Oncogene messenger RNAs for c-myc, c-erbB and c-ras were increased in a specific temporal sequence after the addition of serum. Compounds that are proposed to exert their actions by the stimulation of cell growth were tested for their effect on oncogene transcription in IMR-90 fibroblasts. The tumor promoter tetradecanoyl phorbol acetate (TPA) was found to selectively induce the transcription of c-myc without observable effect on the transcription of the other oncogenes studied, and without inducing cell division. The inactive analog, phorbol didecanoate (PDD), and two complete carcinogens dimethylbenzanthracene (DMBA) and 4-nitro quinoline-1-oxide (4NQO) were without effect on the transcription of the genes studied. These results suggest that the complete ordered sequence of gene transcription is necessary to achieve the physiologic response of cell division, and that classical promoters and complete carcinogens achieve their effects through different pathways.

  4. Antimutagenic and anticarcinogenic effects of Phyllanthus amarus.

    PubMed

    Sripanidkulchai, B; Tattawasart, U; Laupatarakasem, P; Vinitketkumneun, U; Sripanidkulchai, K; Furihata, C; Matsushima, T

    2002-01-01

    This study aimed to examine the antimutagenic and anticarcinogenic potential of Phyllanthus amarus Schum. et Thonn. using the bacterial preincubation mutation assay and an in-vivo alkaline elution method for DNA single-strand breaks in hamster liver cells. The aqueous extract of the entire plant showed an antimutagenic effect against induction by 2-aminofluorene (AF2), 2-aminoanthracene (2AA) and 4-nitroquinolone-1-oxide (4-NQO) in Salmonella typhimurium strains TA98 and TA100, and in Escherichia coli WP2 uvrA/pKM101. All the results were dose-dependent; however, inhibition of N-ethyl-N-nitrosoguanidine (ENNG)-induced mutagenesis was observed only with S. typhimurium TA100. The extract also exhibited activity against 2-nitrofluorene (2NF) and sodium azide-induced mutagenesis with S. typhimurium TA98 and TA100, respectively. Based on the alkaline elution method, the plant extract prevented in vivo DNA single-strand breaks caused by dimethylnitrosamine (DMN) in hamster liver cells. When the extract was administered 30 min prior to the administration of DMN, the elution rate constant decreased more than 2.5 times, compared to that of control. These results indicate that P. amarus possesses antimutagenic and antigenotoxic properties. PMID:11924760

  5. Studies on the metabolism and biological effects of nitropyrene and related nitro-polycyclic aromatic compounds in diploid human fibroblasts.

    PubMed

    Maher, V M; Patton, J D; McCormick, J J

    1988-03-01

    Nitro derivatives of polycyclic aromatic hydrocarbons are produced primarily as the result of incomplete combustion. Nitropyrenes have been identified as primary mutagenic compounds of diesel emission particulate and are tumorigenic in laboratory animals. Since nitropyrenes do not react directly with DNA, their effects presumably are mediated through cellular conversion of the parent compounds into reactive species. For example, 1-nitropyrene (1-NP) is activated by enzymatic reduction to 1-nitrosopyrene (1-NOP), followed by reduction to the hydroxylamine, which undergoes decomposition to yield a nitrenium ion, that reacts with DNA. The cytotoxic effects of 1-nitropyrene and 1-nitrosopyrene were compared in fibroblasts from normal persons, from excision-repair-deficient xeroderma pigmentosum (XP) patients, and from a patient with an inherited predisposition to malignant melanoma of the skin (hereditary cutaneous malignant melanoma [HCMM]). HCMM cells are more sensitive than normal cells to the cytotoxic and mutagenic effects of 4-nitroquinoline-1-oxide, and they form more DNA adducts per concentration of this agent than do normal cells. However, the HCMM cells exhibit the same sensitivity as normal cells to 4-hydroxyaminoquinoline-1-oxide, which suggests they are more capable than normal cells of metabolizing the parent compound into a more reactive form. On the basis of concentration, 1-NOP was much more cytotoxic than 1-NP. With both compounds, the normal cells exhibited a shoulder on their survival curves that was lacking for the XP cells. The dose of 1-NP giving 37% survival was 46 microM for a series of four normal cell lines, 22 microM for the HCMM cell line tested, and 12 microM for the XP cell line. The slope of the 1-nitropyrene survival curve for XP cells was 2.5 times steeper than the slope of the curve of the normal cells; the slope of the 1-NP survival curve for the HCMM cells was intermediate between the XP cells and the normal fibroblasts. The slope

  6. Studies on the oxidation of hexamethylbenzene 1: Oxidation of hexamethylbenzene with nitric acid

    NASA Technical Reports Server (NTRS)

    Chiba, K.; Tomura, S.; Mizuno, T.

    1986-01-01

    The oxidative reaction of hexamethylbenzene (HMB) with nitric acid was studied, and the hitherto unknown polymethylbenzenepolycarboxylic acids were isolated: tetramethylphthalic anhydride, tetramethylisophthalic acid, 1,3,5-, 1,2,4- and 1,2,3-trimethylbenzenetricarboxylic acids. When HMB was warmed with 50% nitric acid at about 80 C, tetramethylphthalic anhydride and tetramethylisophthalic acid were initially produced. The continued reaction led to the production of trimethylbenzenetricarboxylic acids, but only slight amounts of dimethylbenzenetetracarboxylic acids were detected in the reaction mixture. Whereas tetramethylphthalic anydride and tetramethylisophthalic acid were obtained, pentamethylbenzoic acid, a possible precursor of them, was scarcely produced. On the other hand, a yellow material extracted with ether from the initial reaction mixture contained bis-(nitromethyl)prehnitene (CH3)4C6(CH2NO2)2, which was easily converted into the phthalic anhydride.

  7. [Stability and catalytic properties of o-diphenol oxidase. 1. Oxidation of o-diphenols].

    PubMed

    Butovich, I A

    1986-01-01

    o-Diphenoloxidase from potato tubers is inactivated in the course of the oxidation reaction of o-diphenols at the level of the enzyme-substrate complex. At 25 degrees C of the reaction mixture the enzyme inactivation rate constants (Kin) in oxidation of 10 mM solutions of the substrates were: for pyrocatechol--0.48 min-1; 3,4-dihydroxyphenylethylamine (DOP-amine)--0.52 min-1; 3,4-dihydroxyphenylalanine (DOPA)--0.17 min-1; noradrenaline--0.12 min-1; 3,4-dihydroxybenzaldehyde (DHBA)--0.032 min-1; 3,4-dihydroxybenzoic acid (DHBAc)--0.01 min-1; gallic acid--0.01 min-1. Kin of the enzyme in oxidation of pyrocatechol does not depend practically on pH, ionic strength and polarity of the medium, but rises with its temperature. For a temperature range from 20 to 40 degrees C the effective activation energy calculated in terms of the Arrhenius equation is equal to 28 kJ/mol and the preexponential value for the given preparation was 38 850 min-1. The enzyme activity is determined by the substituent nature in the substrate molecule: electron-donor groups (--CH2--) accelerate the oxidation as compared to nonsubstituted pyrocatechol and electron-acceptor groups (--COOH, --CHO) make it more difficult. If the o-diphenoloxidase activity in oxidation of a 10 mM solution of pyrocatechol is 100%, then the oxidation rate of DOP-amine taken in the same concentration would be 111, DOPA--61, noradrenaline--24, DOBA--2,7, DHBA--0.7, gallic acid--0.8%.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3080835

  8. Nonmethane hydrocarbons at Pico Mountain, Azores: 1. Oxidation chemistry in the North Atlantic region

    NASA Astrophysics Data System (ADS)

    Helmig, D.; Tanner, D. M.; Honrath, R. E.; Owen, R. C.; Parrish, D. D.

    2008-10-01

    Measurements of nonmethane hydrocarbons (NMHC) at the Pico Mountain observatory at 2225 m asl on Pico Island, Azores, Portugal, from August 2004 to August 2005 (in part overlapping with the field campaign of the International Consortium on Atmospheric Research on Transport and Transformation study) were used to investigate NMHC sources and seasonal oxidation chemistry in the central North Atlantic region. Levels of anthropogenic NMHC were characteristic of the marine free troposphere. Their concentrations were low compared to continental sites at higher northern latitudes, but higher than data reported from a similarly located Pacific mountain site at Mauna Loa Observatory, Hawaii. These higher NMHC levels are indicative of a greater influence of the adjacent continents on air composition at Pico. Substantially enhanced NMHC concentrations during the summers of 2004 and 2005 were attributed to long-range transport of biomass burning plumes originating from fires in northern Canada, Alaska, and Siberia. This finding exemplifies the continuing impact of biomass burning plumes on atmospheric composition and chemistry many days downwind of these emission sources. Seasonal cycles with lower NMHC concentrations and lower ratios of more reactive to less reactive NMHC during summer reflect the higher degree of photochemical processing occurring during transport. The NMHC concentrations indicate no significant role of chlorine atom oxidation on NMHC. Ozone above 35 ppbv was measured at Pico Mountain throughout all seasons. Enhanced ozone levels were observed in air that had relatively "fresh" photochemical signatures (e.g., ln [propane]/[ethane] > -2.5). During spring-summer air that was more processed ("older" air with ln [propane]/[ethane] < -2.5) on average had lower ozone levels (down to <20 ppbv). This relationship indicates that conditions in the lower free troposphere over the mid-North Atlantic during the spring and summer lead to net photochemical ozone destruction while air is photochemically aging during transport to Pico. This behavior contrasts to that in the mid-North Pacific where other recent studies have found that the photochemistry is more nearly ozone neutral.

  9. Apollo 16 mission anomaly report no. 1: Oxidizer deservicing tank failure

    NASA Technical Reports Server (NTRS)

    1972-01-01

    The command module reaction control system is emptied of all remaining propellant using ground support equipment designed to provide an acid/base neutralization of the propellant in both the liquid and gaseous phases so that it may be disposed of safely. During the deactivation operation of the oxidizer from the Apollo 16 command module on 7 May 1972, the scrubber tank of the decontamination unit exploded, destroying the ground support equipment unit and damaging the building that housed the operation. Only minor injuries were received by the personnel in the area and the command module was not damaged. Test results show that the failure was caused by an insufficient quantity of neutralizer for the quantity of oxidizer. This insufficiency lead to exothermic nitration-type reactions which produced large quantities of gas at a very high rate and failed the decontamination tank.

  10. TIA1 oxidation inhibits stress granule assembly and sensitizes cells to stress-induced apoptosis

    PubMed Central

    Arimoto-Matsuzaki, Kyoko; Saito, Haruo; Takekawa, Mutsuhiro

    2016-01-01

    Cytoplasmic stress granules (SGs) are multimolecular aggregates of stalled translation pre-initiation complexes that prevent the accumulation of misfolded proteins, and that are formed in response to certain types of stress including ER stress. SG formation contributes to cell survival not only by suppressing translation but also by sequestering some apoptosis regulatory factors. Because cells can be exposed to various stresses simultaneously in vivo, the regulation of SG assembly under multiple stress conditions is important but unknown. Here we report that reactive oxygen species (ROS) such as H2O2 oxidize the SG-nucleating protein TIA1, thereby inhibiting SG assembly. Thus, when cells are confronted with a SG-inducing stress such as ER stress caused by protein misfolding, together with ROS-induced oxidative stress, they cannot form SGs, resulting in the promotion of apoptosis. We demonstrate that the suppression of SG formation by oxidative stress may underlie the neuronal cell death seen in neurodegenerative diseases. PMID:26738979

  11. Synthesis, scale-up, and characterization of 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105)

    SciTech Connect

    Pagoria, P. F.

    1998-04-27

    We have synthesized 4OOg of the new, insensitive, energetic heterocycle, 2,6-diamino-3,5-dinitropyrazine-l-oxide (LLM-105) with 81% the energy of HMX and excellent thermal stability. The synthesis is a three step reaction sequence from the commercially available starting material, 2,6-dichloropyrazine, with an overall yield of 36%. In this paper we will describe the scale-up of the synthesis of LLM- 105 and report on performance and shock sensitivity experiments performed on this material.

  12. (3R,4S)-3,4-Isopropylidenedioxy-5-phenylsulfonylmethyl-3,4-dihydro-2H-pyrrole 1-oxide

    PubMed Central

    Flores, Mari Fe; Garcia, P.; M. Garrido, Narciso; Sanz, Francisca; Diez, David

    2011-01-01

    The title compound, C14H17NO5S, was prepared by oxidation of (2R,3S,4R)-2-phenyl­sulfonyl­methyl-1-hy­droxy-3,4-iso­pro­pyl­idene­dioxy­pyrrolidine. Its crystal structure confirms unequivocally its configuration. Two inter­molecular C—H⋯O inter­actions help to establish the packing. PMID:21754431

  13. Genotoxicity studies with the unstable Zeste-White (UZ) system of Drosophila melanogaster: Results with ten carcinogenic compounds

    SciTech Connect

    Batiste-Alentorn, M.; Xamena, N.; Creus, A.; Marcos, R. )

    1991-01-01

    To increase the number of chemicals tested using the Zeste-White (UZ) somatic mutation assay, ten selected carcinogens (acetamide, acrylamide, benzo({alpha})pyrene, cyclophosphamide, diethylstilbestrol, 4-nitroquinoline N-oxide, propyleneimine, safrole, thiourea, and o-toluidine) have been evaluated in this assay. The results show that all the compounds tested produce significant increases in the eye spot frequency at, at least, one of the concentrations assayed, indicating that the Zeste-White assay appears to be highly sensitive to these carcinogenic compounds. That is in agreement with data previously reported by other authors.

  14. The Saccharomyces cerevisiae gene PSO5/RAD16 is involved in the regulation of DNA damage-inducible genes RNR2 and RNR3.

    PubMed

    Paesi-Toresan, S O; Maris, A F; Brendel, M; Henriques, J A

    1998-08-01

    The expression of beta-galactosidase from DNA damage-inducible RNR2-lacZ and RNR3-lacZ fusion constructs was compared in wild-type (WT) and pso5/rad16 mutant strains after treatment with five mutagens/oxidative stressors. While exposure to the mutagens UVC, 4NQO and H2O2 induced expression of the RNR2-lacZ and RNR3-lacZ fusion constructs in two WT strains, treatment with the two oxidative stressors tBOOH and paraquat did not. In the pso5-1 mutant induction of RNR2-lacZ was largely reduced after UVC and H2O2 while there was no significant induction of beta-galactosidase expression after 4NQO treatment for this construct. For RNR3-lacZ there was strongly reduced expression of pso5-1 after UVC and 4NQO while H2O2 failed to induce expression of beta-galactosidase. In the WT strains the ranking of the inducing power of the mutagens at 90% survival (as measured in the pso5-1 mutant) was 4NQO>UVC>H2O2. Though the WT strains were clearly more resistant that the pso5-1 mutant to the two oxidative stressors paraquat and tBOOH, these substances failed to significantly enhance expression of the RNR2-lacZ and RNR3-lacZ fusion constructs in both the WT and the pso5-1 mutant. Our data suggest that Pso5p/Rad16p has a function in the signal transducing pathway controlling DNA damage-inducible components of nucleotide excision repair. PMID:9724415

  15. Comparison of the Isothermal Oxidation Behavior of As-Cast Cu-17%Cr and Cu-17%Cr-5%Al. Part 1; Oxidation Kinetics

    NASA Technical Reports Server (NTRS)

    Raj. Sai V.

    2008-01-01

    The isothermal oxidation kinetics of as-cast Cu-17%Cr and Cu-17%Cr-5%Al in air were studied between 773 and 1173 K under atmospheric pressure. These observations reveal that Cu- 17%Cr-5%Al oxidizes at significantly slower rates than Cu-17%Cr. The rate constants for the alloys were determined from generalized analyses of the data without an a priori assumption of the nature of the oxidation kinetics. Detailed analyses of the isothermal thermogravimetric weight change data revealed that Cu-17%Cr exhibited parabolic oxidation kinetics with an activation energy of 165.9 +/- 9.5 kJ/mol. In contrast, the oxidation kinetics for the Cu-17%Cr- 5%Al alloy exhibited a parabolic oxidation kinetics during the initial stages followed by a quartic relationship in the later stages of oxidation. Alternatively, the oxidation behavior of Cu-17%CR- 5%Al could be better represented by a logarithmic relationship. The parabolic rate constants and activation energy data for the two alloys are compared with literature data to gain insights on the nature of the oxidation mechanisms dominant in these alloys.

  16. Comparison of the Isothermal Oxidation Behavior of As-Cast Cu-17 Percent Cr and Cu-17 Percent Cr-5 Percent Al. Part 1; Oxidation Kinetics

    NASA Technical Reports Server (NTRS)

    Raj, S. V.

    2008-01-01

    The isothermal oxidation kinetics of as-cast Cu-17%Cr and Cu-17%Cr-5%Al in air were studied between 773 and 1173 K under atmospheric pressure. These observations reveal that Cu-17%Cr-5%Al oxidizes at significantly slower rates than Cu-17%Cr. The rate constants for the alloys were determined from generalized analyses of the data without an a priori assumption of the nature of the oxidation kinetics. Detailed analyses of the isothermal thermogravimetric weight change data revealed that Cu-17%Cr exhibited parabolic oxidation kinetics with an activation energy of 165.9+/-9.5 kJ/mol. In contrast, the oxidation kinetics for the Cu-17%Cr-5%Al alloy exhibited a parabolic oxidation kinetics during the initial stages followed by a quartic relationship in the later stages of oxidation. Alternatively, the oxidation behavior of Cu-17%CR-5%Al could be better represented by a logarithmic relationship. The parabolic rate constants and activation energy data for the two alloys are compared with literature data to gain insights on the nature of the oxidation mechanisms dominant in these alloys.

  17. Comparison of the Isothermal Oxidation Behavior of As-Cast Cu-17%Cr and Cu-17%Cr-5%Al. Part 1; Oxidation Kinetics

    NASA Technical Reports Server (NTRS)

    Raj. Sai V.

    2008-01-01

    The isothermal oxidation kinetics of as-cast Cu-17%Cr and Cu-17%Cr-5%Al in air were studied between 773 and 1173 K under atmospheric pressure. These observations reveal that Cu- 17%Cr-5%Al oxidizes at significantly slower rates than Cu-17%Cr. The rate constants for the alloys were determined from generalized analyses of the data without an a priori assumption of the nature of the oxidation kinetics. Detailed analyses of the isothermal thermogravimetric weight change data revealed that Cu-17%Cr exhibited parabolic oxidation kinetics with an activation energy of 165.9 9.5 kJ mol-1. In contrast, the oxidation kinetics for the Cu-17%Cr- 5%Al alloy exhibited a parabolic oxidation kinetics during the initial stages followed by a quartic relationship in the later stages of oxidation. Alternatively, the oxidation behavior of Cu-17%CR- 5%Al could be better represented by a logarithmic relationship. The parabolic rate constants and activation energy data for the two alloys are compared with literature data to gain insights on the nature of the oxidation mechanisms dominant in these alloys.

  18. Photo-electrochemical Oxidation of Organic C1 Molecules over WO3 Films in Aqueous Electrolyte: Competition Between Water Oxidation and C1 Oxidation.

    PubMed

    Reichert, Robert; Zambrzycki, Christian; Jusys, Zenonas; Behm, R Jürgen

    2015-11-01

    To better understand organic-molecule-assisted photo-electrochemical water splitting, photo-electrochemistry and on-line mass spectrometry measurements are used to investigate the photo-electrochemical oxidation of the C1 molecules methanol, formaldehyde, and formic acid over WO3 film anodes in aqueous solution and its competition with O2 evolution from water oxidation O2 (+) and CO2 (+) ion currents show that water oxidation is strongly suppressed by the organic species. Photo-electro-oxidation of formic acid is dominated by formation of CO2 , whereas incomplete oxidation of formaldehyde and methanol prevails, with the selectivity for CO2 formation increasing with increasing potential and light intensity. The mechanistic implications for the photo-electro-oxidation of the organic molecules and its competition with water oxidation, which could be derived from this novel approach, are discussed.

  19. Differential regulation of Krüppel-like factor family transcription factor expression in neonatal rat cardiac myocytes: effects of endothelin-1, oxidative stress and cytokines.

    PubMed

    Cullingford, Timothy E; Butler, Matthew J; Marshall, Andrew K; Tham, El Li; Sugden, Peter H; Clerk, Angela

    2008-06-01

    Krüppel-like transcription factors (Klfs) modulate fundamental cell processes. Cardiac myocytes are terminally-differentiated, but hypertrophy in response to stimuli such as endothelin-1. H2O2 or cytokines promote myocyte apoptosis. Microarray studies of neonatal rat myocytes identified several Klfs as endothelin-1-responsive genes. We used quantitative PCR for further analysis of Klf expression in neonatal rat myocytes. In response to endothelin-1, Klf2 mRNA expression was rapidly increased ( approximately 9-fold; 15-30 min) with later increases in expression of Klf4 and Klf6 ( approximately 5-fold; 30-60 min). All were regulated as immediate early genes (cycloheximide did not inhibit the increases in expression). Klf5 expression was increased at 1-2 h ( approximately 13-fold) as a second phase response (cycloheximide inhibited the increase). These increases were transient and attenuated by U0126. H2O2 increased expression of Klf2, Klf4 and Klf6, but interleukin-1beta or tumor necrosis factor alpha downregulated Klf2 expression with no effect on Klf4 or Klf6. Of the Klfs which repress transcription, endothelin-1 rapidly downregulated expression of Klf3, Klf11 and Klf15. The dynamic regulation of expression of multiple Klf family members in cardiac myocytes suggests that, as a family, they are actively involved in regulating phenotypic responses (hypertrophy and apoptosis) to extracellular stimuli.

  20. (3R,4S)-3,4-Isopropyl­idenedioxy-3,4-dihydro-2H-pyrrole 1-oxide

    PubMed Central

    Flores, Mari Fe; Garcia, Pilar; M. Garrido, Narciso; Sanz, Francisca; Diez, David

    2011-01-01

    The title compound C7H11NO3 was prepared by intra­molecular nucleophilic displacement of 2,3-O-iso-propyl­idene-d-erythronolactol. There are two mol­ecules in the asymmetric unit, which are related by a pseudo-inversion centre. The crystal structure determination confirms unequivocally the configuration of the chiral centres as 3S,4R. In the crystal structure, inter­molecular C—H⋯O inter­actions link the mol­ecules (into infinite zigzag chains along the a axis. PMID:21754432

  1. Toxicity and bioaccumulation of the booster biocide copper pyrithione, copper 2-pyridinethiol-1-oxide, in gill tissues of Salvelinus fontinalis (brook trout).

    PubMed

    Borg, Damon Andrew; Trombetta, Louis David

    2010-04-01

    This investigation studied the acute effects of copper pyrithione (CuPT) exposure on juvenile brook trout, Salvelinus fontinalis. Morphologic changes, copper bioaccumulation, and markers of oxidative stress in gill tissue were studied. Juvenile brook trout were treated with one of six experimental doses of CuPT (2-64 microg/L) for 2 hours. A seventh group served as a control population. Inductively coupled plasma atomic absorbance spectrophotometry (ICPAAS) analysis demonstrates significantly increased levels of copper in gill tissue (p < 0.001). Results from scanning electron microscopy and histological analysis demonstrate the formation of club-shaped lamella, edema, fusion of secondary lamella, loss of microridge structures and epithelial exfoliation. Transmission electron microscopy revealed altered morphology of chloride cells, including the swollen appearance of mitochondria with disruption of internal cristae and lipid membrane disruption. Thiobarbituric acid reactive substance (TBARS) assays demonstrated increased levels of lipid peroxidation products in gill tissue. Assays for the total antioxidant capacity of gill tissue revealed significantly lowered antioxidant levels. This data indicates that CuPT is potentially harmful to nontarget aquatic organisms at environmentally relevant doses.

  2. Novel antimutagenic factors derived from the edible mushroom Agrocybe cylindracea.

    PubMed

    Taira, Kentaro; Miyashita, Yukiko; Okamoto, Keinosuke; Arimoto, Sakae; Takahashi, Eizo; Negishi, Tomoe

    2005-10-01

    Studies have shown that certain foods contain compounds with antigenotoxic activities. Here, we ask if dried powders and/or extracts from three edible mushrooms, Agrocybe cylindracea, Lentinula edodes and Pleurotus ostreatus, have a mitigating effect on genotoxicity. We used two in vivo assays: the Drosophila DNA repair test and the Drosophila wing spot test (also known as SMART) which measures somatic mutation and recombination. Eight carcinogens were tested with the mushroom powders: 2-AAF, aflatoxin B1, DMBA, IQ, MeIQx, MNU NDMA, and 4NQO. We found that A. cylindracea and P. ostreatus powders can suppress DNA damage induced by each of the mutagens we tested. In contrast, L. edodes has an inhibitory effect on DNA damage induced by only a sub-set of mutagens, namely aflatoxin B1, NDMA, MNU and 4NQO. In addition, A. cylindracea extracts were able to suppress somatic cell mutation induced by aflatoxin B1, MMC, MNU, NDMA, NMOR and 4NQO. These results suggest that Agrocybe genus mushrooms contain factors with antigenotoxic activity, including anti-recombinogenic activity. Furthermore, the antigenotoxic activity of A. cylindracea powder can be extracted in water but not in ethyl acetate or methanol, and is sensitive to heat treatment. The data suggest that there is a novel antigenotoxic factor(s) in A. cylindracea, possibly in the form of a peptide or protein.

  3. Structure and Function of CinD (YtjD) of Lactococcus lactis, a Copper-Induced Nitroreductase Involved in Defense against Oxidative Stress ▿

    PubMed Central

    Mermod, Mélanie; Mourlane, Frédéric; Waltersperger, Sandro; Oberholzer, Anselm E.; Baumann, Ulrich; Solioz, Marc

    2010-01-01

    In Lactococcus lactis IL1403, 14 genes are under the control of the copper-inducible CopR repressor. This so-called CopR regulon encompasses the CopR regulator, two putative CPx-type copper ATPases, a copper chaperone, and 10 additional genes of unknown function. We addressed here the function of one of these genes, ytjD, which we renamed cinD (copper-induced nitroreductase). Copper, cadmium, and silver induced cinD in vivo, as shown by real-time quantitative PCR. A knockout mutant of cinD was more sensitive to oxidative stress exerted by 4-nitroquinoline-N-oxide and copper. Purified CinD is a flavoprotein and reduced 2,6-dichlorophenolindophenol and 4-nitroquinoline-N-oxide with kcat values of 27 and 11 s−1, respectively, using NADH as a reductant. CinD also exhibited significant catalase activity in vitro. The X-ray structure of CinD was resolved at 1.35 Å and resembles those of other nitroreductases. CinD is thus a nitroreductase which can protect L. lactis against oxidative stress that could be exerted by nitroaromatic compounds and copper. PMID:20562311

  4. Construction of mutants of Salmonella typhimurium deficient in 8-hydroxyguanine DNA glycosylase and their sensitivities to oxidative mutagens and nitro compounds.

    PubMed

    Suzuki, M; Matsui, K; Yamada, M; Kasai, H; Sofuni, T; Nohmi, T

    1997-10-24

    8-Hydroxyguanine (8-OH-G) DNA glycosylase is an enzyme involved in repair of oxidative DNA damage, e.g., 8-OH-G in DNA. In order to assess the roles of 8-OH-G in spontaneous and chemically-induced mutagenesis, the mutMST gene encoding 8-OH-G DNA glycosylase of Salmonella typhimurium was disrupted in several Ames tester strains, i.e., S. typhimurium TA1535 (hisG46, uvrB-, rfa), TA1975 (hisG46, uvr+, rfa) and TA102 (hisG428, uvr+, rfa). The spontaneous mutation frequencies were increased 2.4 and 1.6 times, respectively, by the mutMST deletions in strains TA1535 and TA1975, which are spontaneously reverted to His+ by mutations mainly at G:C base pairs. The resulting strains YG3001 (TA1535 delta mutMST) and YG3002 (TA1975 delta mutMST) were 2 to 8 times more sensitive to the mutagenicities of methylene blue plus visible light, neutral red plus visible light and 2-nitrofluorene than the parent strains. The strain YG3002 but not YG3001 was about 30 times more sensitive to the mutagenicity of 4-nitroquinoline N-oxide than the parent strain TA1975. Neither hydrogen peroxide nor phenazine methosulfate was mutagenic in the mutMST-deletion strains as well as in the parent strains. In contrast, the mutMST deletion did not affect the spontaneous mutation frequency of strain TA102, which has an A:T base pair at the critical site for reversion. The sensitivities of strain TA102 to the chemicals were not enhanced by the mutMST deletion except for hydrogen peroxide. These results suggest that 8-OH-G in DNA plays important roles in spontaneous mutagenesis occurring at G:C base pairs in S. typhimurium, and some nitro aromatics such as 4-nitroquinoline N-oxide or 2-nitrofluorene as well as the photosensitizers plus visible light can produce 8-OH-G in DNA, thereby inducing mutations. In the case of 4-nitroquinoline N-oxide, 8-OH-G rather than DNA adducts seems to play major roles in mutagenesis in uvr+ background. The new strains could be useful for the evaluation of the roles of 8-OH

  5. Variety-based variation in the antimutagenic potential of various vegetables and lack of its correlation with their antioxidant capacity.

    PubMed

    Bandyopadhyay, Nilantana; Gautam, Satyendra; Sharma, Arun

    2013-08-01

    As mutation causes many life-threatening diseases including cancer, a diet enriched with specific vegetables having potential to reduce mutagenesis possesses immense significance. In this study, 41 commonly used vegetables from diverse botanical taxa were evaluated and compared for their relative antimutagenic potential using standard assays [Escherichia coli RNA polymerase β (rpoB)-based Rif(S) → Rif(R) assay and Ames test] against known mutagens (UV, gamma radiation, 4-nitroquinoline-N-oxide and ethylmethanesulphonate). Significant differences in antimutagenicity were observed even among the cultivars within the same species, as well as at other phylogenetic levels such as genus or family. The effect of cooking in terms of boiling (aquathermal treatment), on the antimutagenicity of these vegetables, was also investigated. In majority of the cases, aquathermal treatment did not affect the antimutagenic potential. The antimutagenicity of these vegetables was not found to correlate well with their antioxidant properties.

  6. Antioxidant and antigenotoxic effects of rosemary (Rosmarinus officinalis L.) extracts in Salmonella typhimurium TA98 and HepG2 cells.

    PubMed

    Zegura, Bojana; Dobnik, David; Niderl, Maša Hojnik; Filipič, Metka

    2011-09-01

    In the present study the chemopreventive effects of water soluble AquaROX(®) 15 and oil soluble VivOX(®) 40 rosemary extracts against 4-nitroquinoline-N-oxide (NQNO) and 2-amino-3-methyl-3H-imidazo[4,5-F]quinoline (IQ) induced mutagenicity in the reverse mutation assays with Salmonella typhimurium TA98 and against t-butyl hydroperoxide (t-BOOH), benzo(a)pyrene (BaP) and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) induced DNA damage in HepG2 cells were studied, applying the comet assay. The results showed comparable protective effect of AquaROX and VivOX against oxidative DNA damage, whereas protection against indirect active genotoxic carcinogens was more efficient by VivOX.

  7. Histological changes in the submandibular glands of rats after intraductal injection of chemical carcinogens.

    PubMed

    Takeuchi, J; Miura, K; Usizima, H; Katoh, Y

    1975-01-01

    Carcinogens injected into the excretory canal of submandibular gland of Donryu rats revealed the following histologic changes in salivary glands. 20-Methylcholanthrene induced squamous cell metaplasia, fibrosis in the early stages, and "benign lymphoepithelial lesion"-like pattern after 3 months. Dense hyalinization occurred after 4-5 months with so-called "mixed tumor"-like pattern. In the later stages epidermoid carcinoma and fibrosarcoma were observed. 9, 10-Dimethylbenzanthracene caused degenerative change, metaplasia, fibrosis and cell infiltration, and later carcinoma and sarcoma appeared at a high rate. 4-Nitroquinoline-N-oxide led to dense hyalinization and so-called "mixed tumor"-like pattern was observed in many specimens. N-nitroso-N-methyl urethane and N-methyl-N-nitroso-N'-nitroguanidine revealed metaplastic changes, fibrosis and lymphoid infiltration. Scarlet red induced remarkable infiltration and aggregation of lymphoid cells, showing benign "lymphoepithelial lesion"-like pattern.

  8. Calorimetric and computational study of thiacyclohexane 1-oxide and thiacyclohexane 1,1-dioxide (thiane sulfoxide and thiane sulfone). Enthalpies of formation and the energy of the S=O bond.

    PubMed

    Roux, María Victoria; Temprado, Manuel; Jiménez, Pilar; Dávalos, Juan Zenón; Notario, Rafael; Guzmán-Mejía, Ramón; Juaristi, Eusebio

    2003-03-01

    A rotating-bomb combustion calorimeter specifically designed for the study of sulfur-containing compounds [J. Chem. Thermodyn. 1999, 31, 635] has been used for the determination of the enthalpy of formation of thiane sulfone, 4, Delta(f)H(o) m(g) = -394.8 +/- 1.5 kJ x mol(-1). This value stands in stark contrast with the enthalpy of formation reported for thiane itself, Delta(f)H(o) m(g) = -63.5 +/- 1.0 kJ x mol(-1), and gives evidence of the increased electronegativity of the sulfur atom in the sulfonyl group, which leads to significantly stronger C-SO2 bonds. Given the known enthalpy of formation of atomic oxygen in the gas phase, Delta(f)H(o) m(O,g) = +249.18 kJ x mol(-1), and the reported bond dissociation energy for the S=O bond in alkyl sulfones, BDE(S=O) = +470.0 kJ x mol(-1), it was possible to estimate the enthalpy of formation of thiane sulfoxide, 5, a hygroscopic compound not easy to use in experimental calorimetric measurements, Delta(f)H(o) m(5) = -174.0 kJ x mol(-1). The experimental enthalpy of formation of both 4 and 5 were closely reproduced by theoretical calculations at the G2(MP2)+ level, Delta(f)H(o) m(4) = -395.0 kJ x mol(-1) and Delta(f)H(o) m(5) = -178.0 kJ x mol(-1). Finally, calculated G2(MP2)+ values for the bond dissociation energy of the S=O bond in cyclic sulfoxide 5 and sulfone 4 are +363.7 and +466.2 kJ x mol(-1), respectively. PMID:12608789

  9. Calorimetric and computational study of thiacyclohexane 1-oxide and thiacyclohexane 1,1-dioxide (thiane sulfoxide and thiane sulfone). Enthalpies of formation and the energy of the S=O bond.

    PubMed

    Roux, María Victoria; Temprado, Manuel; Jiménez, Pilar; Dávalos, Juan Zenón; Notario, Rafael; Guzmán-Mejía, Ramón; Juaristi, Eusebio

    2003-03-01

    A rotating-bomb combustion calorimeter specifically designed for the study of sulfur-containing compounds [J. Chem. Thermodyn. 1999, 31, 635] has been used for the determination of the enthalpy of formation of thiane sulfone, 4, Delta(f)H(o) m(g) = -394.8 +/- 1.5 kJ x mol(-1). This value stands in stark contrast with the enthalpy of formation reported for thiane itself, Delta(f)H(o) m(g) = -63.5 +/- 1.0 kJ x mol(-1), and gives evidence of the increased electronegativity of the sulfur atom in the sulfonyl group, which leads to significantly stronger C-SO2 bonds. Given the known enthalpy of formation of atomic oxygen in the gas phase, Delta(f)H(o) m(O,g) = +249.18 kJ x mol(-1), and the reported bond dissociation energy for the S=O bond in alkyl sulfones, BDE(S=O) = +470.0 kJ x mol(-1), it was possible to estimate the enthalpy of formation of thiane sulfoxide, 5, a hygroscopic compound not easy to use in experimental calorimetric measurements, Delta(f)H(o) m(5) = -174.0 kJ x mol(-1). The experimental enthalpy of formation of both 4 and 5 were closely reproduced by theoretical calculations at the G2(MP2)+ level, Delta(f)H(o) m(4) = -395.0 kJ x mol(-1) and Delta(f)H(o) m(5) = -178.0 kJ x mol(-1). Finally, calculated G2(MP2)+ values for the bond dissociation energy of the S=O bond in cyclic sulfoxide 5 and sulfone 4 are +363.7 and +466.2 kJ x mol(-1), respectively.

  10. Effects of tannic acid on spontaneous and induced somatic mutations in Drosophila melanogaster.

    PubMed

    Szakmary, A; Knasmüller, S

    1991-05-01

    The effects of tannic acid (TA) alone and in combination with direct acting chemical genotoxins and gamma-radiation were investigated in Somatic Mutation and Recombination Tests (SMARTs) using Drosophila melanogaster. Treatment with TA alone (2.5-15 mmol/l) resulted in a moderate but dose dependent induction of mosaic spots in males and females, indicating that the compound possesses mutagenic and recombinogenic activity. When TA (10 mmol/l) was given simultaneously with MMS, 4-NQO and cis-DDP, a potentiating effect on their mutagenicity was observed in males whereas in females no such increase was measured. The frequency of 4-NQO induced mosaic spots in males was raised more than threefold in presence of TA, for MMS and cis-DDP the enhancement was approximately 2-fold; with gamma-radiation no synergistic effect occurred. The different response in the two sexes indicates that TA preferentially induces gene mutations and deletions but has no enhancing effect on the number of mosaic spots which are formed as a consequence of recombinogenic events. PMID:1908938

  11. Antimutagenicity of Methanolic Extracts from Anemopsis californica in Relation to Their Antioxidant Activity

    PubMed Central

    Del-Toro-Sánchez, Carmen Lizette; Bautista-Bautista, Nereyda; Blasco-Cabal, José Luis; Gonzalez-Ávila, Marisela; Gutiérrez-Lomelí, Melesio; Arriaga-Alba, Myriam

    2014-01-01

    Anemopsis californica has been used empirically to treat infectious diseases. However, there are no antimutagenic evaluation reports on this plant. The present study evaluated the antioxidant activity in relation to the mutagenic and antimutagenic activity properties of leaf (LME) and stem (SME) methanolic extracts of A. californica collected in the central Mexican state of Querétaro. Antioxidant properties and total phenols of extracts were evaluated using DPPH (1,1-diphenyl-2-picrylhydrazyl) and Folin-Ciocalteu methods, respectively. Mutagenicity was evaluated using the Ames test employing Salmonella enterica serovar Typhimurium strains (TA98, TA100, and TA102), with and without an aroclor 1254 (S9 mixture). Antimutagenesis was performed against mutations induced on the Ames test with MNNG, 2AA, or 4NQO. SME presented the highest antioxidant capacity and total phenolic content. None of the extracts exhibited mutagenicity in the Ames test. The extracts produced a significant reduction in 2AA-induced mutations in S. typhimurium TA98. In both extracts, mutagenesis induced by 4NQO or methyl-N′-nitro-N-nitrosoguanidine (MNNG) was reduced only if the exposure of strains was <10 μg/Petri dish. A. californca antioxidant properties and its capacity to reduce point mutations render it suitable to enhance medical cancer treatments. The significant effect against antimutagenic 2AA suggests that their consumption would provide protection against carcinogenic polycyclic aromatic compounds. PMID:25152760

  12. Increase in clonal variation in Chinese hamster ovary cells after treatment with mutagens

    SciTech Connect

    Zdzienicka, M.; Cupido, M.; Simons, J.W.

    1985-03-01

    Clonal variation has been studied in CHO cells. The variant phenotype was an altered morphology of clones in agar: the parental CHO cells give rise to solid clumps of cells (wild-type colonies); occasionally, dispersed colonies arise, and the cells display an invasive growth in agar (INGA-type colonies). The frequency of this altered phenotype can be enhanced by treatment with a variety of mutagens (EMS, ENU, 4NQO, N-Ac-AAF, ultraviolet light, and X-irradiation). Enhancement was not due to a selective killing of wild-type cells or to a side-effect of cytotoxicity, which suggests that DNA damage is the cause of the altered phenotype. The INGA-trait breeds true, but most of the isolated clones have an inherent instability.

  13. DNA Repair in Human Cells Exposed to Combinations of Carcinogenic Agents

    SciTech Connect

    Setlow, R. B.; Ahmed, F. E.

    1980-01-01

    Normal human and XP2 fibroblasts were treated with UV plus UV-mimetic chemicals. The UV dose used was sufficient to saturate the UV excision repair system. Excision repair after combined treatments was estimated by unscheduled DNA synthesis, BrdUrd photolysis, and the loss of sites sensitive to a UV specific endonuclease. Since the repair of damage from UV and its mimetics is coordinately controlled we expected that there would be similar rate-limiting steps in the repair of UV and chemical damage and that after a combined treatment the total amount of repair would be the same as from UV or the chemicals separately. The expectation was not fulfilled. In normal cells repair after a combined treatment was additive whereas in XP cells repair after a combined treatment was usually less than after either agent separately. The chemicals tested were AAAF, DMBA-epoxide, 4NQO, and ICR-170.

  14. Suppressive effects of coffee on the SOS responses induced by UV and chemical mutagens.

    PubMed

    Obana, H; Nakamura, S; Tanaka, R

    1986-10-01

    SOS-inducing activity of UV or chemical mutagens (AF-2, 4NQO and MNNG) was strongly suppressed by instant coffee in Salmonella typhimurium TA1535/pSK1002. As decaffeinated instant coffee showed a similarly strong suppressive effect, it would seem that caffeine, a known inhibitor of SOS responses, is not responsible for the effect observed. The suppression was also shown by freshly brewed coffee extracts. However, the suppression was absent in green coffee-bean extracts. These results suggest that coffee contains some substance(s) which, apart from caffeine, suppresses SOS-inducing activity of UV or chemical mutagens and that the suppressive substance(s) are produced by roasting coffee beans.

  15. Dominant mutation in mouse cells associated with resistance to Hoechst 33258 dye, but sensitivity to ultraviolet light and DNA base-damaging compounds

    SciTech Connect

    Debenham, P.G.; Webb, M.B.

    1987-01-01

    A spontaneous derivative of murine L tk- cells has been isolated which has gained a resistance to the cytostatic/lethal effects of high concentrations of Hoechst 33258. The resistant clone HoeR-415 was at least 20-fold more resistant to the dye (D10 dose). HoeR-415 cells have a normal response to X-rays and mitomycin-C and colchicine but were found to show a small sensitivity to UV light, 4NQO, and EMS (1.4, 1.6, and 1.6-fold lower D10 doses, respectively). HoeR-415 cells do not show an increased mutability by EMS. The HoeR phenotype was found to be codominant in hybrids. In order to explain these various characteristics, we suggest that the HoeR-415 mutation may result in an altered topoisomerase activity. Consistent with this we find HoeR-415 cells have an increased sensitivity to novobiocin.

  16. Antimutagenic effects of subfractions of Chaga mushroom (Inonotus obliquus) extract.

    PubMed

    Ham, Seung-Shi; Kim, Soo-Hyun; Moon, Sun-Young; Chung, Mi Ja; Cui, Cheng-Bi; Han, Eun-Kyung; Chung, Cha-Kwon; Choe, Myeon

    2009-01-01

    Inonotus obliquus is a mushroom commonly known as Chaga that is widely used in folk medicine in Siberia, North America, and North Europe. Here, we evaluated the antimutagenic and antioxidant capacities of subfractions of Inonotus obliquus extract. The ethyl acetate extract was separated by vacuum chromatography into three fractions, and the fraction bearing the highest antimutagenic activity was subsequently separated into four fractions by reversed phase (ODS-C18) column chromatography. The most antimutagenic fraction was then separated into two subfractions (subfractions 1 and 2) by normal phase silica gel column chromatography. Ames test analysis revealed that the subfractions were not mutagenic. At 50 μg/plate, subfractions 1 and 2 strongly inhibited the mutagenesis induced in Salmonella typhimurium strain TA100 by the directly acting mutagen MNNG (0.4 μg/plate) by 80.0% and 77.3%, respectively. They also inhibited 0.15 μg/plate 4NQO-induced mutagenesis in TA98 and TA100 by 52.6-62.0%. The mutagenesis in TA98 induced by the indirectly acting mutagens Trp-P-1 (0.15 μg/plate) and B(α)P (10 μg/plate) was reduced by 47.0-68.2% by the subfractions, while the mutagenesis in TA100 by Trp-P-1 and B(α)P was reduced by 70.5-87.2%. Subfraction 1 was more inhibitory than subfraction 2 with regard to the mutagenic effects of 4NQO, Trp-P-1, and B(α)P. Subfractions 1 and 2 also had a strong antioxidant activity against DPPH radicals and were identified by MS, 1H NMR and 13C NMR analyses as 3β-hydroxy-lanosta-8, 24-dien-21-al and inotodiol, respectively. Thus, we show that the 3beta-hydroxy-lanosta-8, 24-dien-21-al and inotodiol components of Inonotus obliquus bear antimutagenic and antioxidative activities. PMID:18992843

  17. Evaluation of a rat tracheal epithelial cell culture assay system to identify respiratory carcinogens

    SciTech Connect

    Steele, V.E.; Arnold, J.T.; Arnold, J.V.; Mass, M.J. )

    1989-01-01

    To evaluate a short-term epithelial cell assay system to detect respiratory carcinogens, primary cultures of rat tracheal epithelial cells were exposed to a series of 17 compounds and scored for morphologically transformed cell colonies 28 days later. The test compounds included known carcinogens and noncarcinogens in volatile or liquid form. Tracheal epithelial cells were isolate from F344 rats, plated onto collagen-coated dishes, and exposed to the test compounds on day 1 for 24 hours. At day 30 the cultures were fixed, stained, and scored for colonies having a density greater than 1,300 cells/mm{sup 2}. With standardized protocols, such colonies are very infrequent in media and solvent control cultures. Concentration levels for each chemical were chosen over a range from nontoxic to toxic levels. Highly positive compounds in this assay included benzo(a)pyrene, benzo(l)aceanthrylene, 3-methylcholanthrene, and formaldehyde. Compounds which were negative in this assay included pyrene, benzo(e)pyrene, and 4-nitroquinoline-N-oxide. Examining the concordance of in vitro results with whole animal carcinogenesis studies revealed an accuracy of 88% with one false-positive and one false-negative compound. The results of these studies indicate that the rat tracheal epithelial cell assay may be useful in identifying potential respiratory carcinogens in our environment.

  18. A Key Role for Old Yellow Enzyme in the Metabolism of Drugs by Trypanosoma cruzi

    PubMed Central

    Kubata, Bruno Kilunga; Kabututu, Zakayi; Nozaki, Tomoyoshi; Munday, Craig J.; Fukuzumi, Shunichi; Ohkubo, Kei; Lazarus, Michael; Maruyama, Toshihiko; Martin, Samuel K.; Duszenko, Michael; Urade, Yoshihiro

    2002-01-01

    Trypanosoma cruzi is the etiological agent of Chagas' disease. So far, first choice anti-chagasic drugs in use have been shown to have undesirable side effects in addition to the emergence of parasite resistance and the lack of prospect for vaccine against T. cruzi infection. Thus, the isolation and characterization of molecules essential in parasite metabolism of the anti-chagasic drugs are fundamental for the development of new strategies for rational drug design and/or the improvement of the current chemotherapy. While searching for a prostaglandin (PG) F2α synthase homologue, we have identified a novel “old yellow enzyme” from T. cruzi (TcOYE), cloned its cDNA, and overexpressed the recombinant enzyme. Here, we show that TcOYE reduced 9,11-endoperoxide PGH2 to PGF2α as well as a variety of trypanocidal drugs. By electron spin resonance experiments, we found that TcOYE specifically catalyzed one-electron reduction of menadione and β-lapachone to semiquinone-free radicals with concomitant generation of superoxide radical anions, while catalyzing solely the two-electron reduction of nifurtimox and 4-nitroquinoline-N-oxide drugs without free radical production. Interestingly, immunoprecipitation experiments revealed that anti-TcOYE polyclonal antibody abolished major reductase activities of the lysates toward these drugs, identifying TcOYE as a key drug-metabolizing enzyme by which quinone drugs have their mechanism of action. PMID:12417633

  19. Combination of ozonation, activated carbon, and biological aerated filter for advanced treatment of dyeing wastewater for reuse.

    PubMed

    Zou, Xiao-Ling

    2015-06-01

    Laboratorial scale experiments were performed to investigate and evaluate the performance and removal characteristics of organics, color, and genotoxicity by an integrated process including ozonation, activated carbon (AC), and biological aerated filter (BAF) for recycling biotreated dyeing wastewater (BTDW) collected from a cotton textile factory. Influent chemical oxygen demand (COD) in the range of 156 - 252 mg/L, 5-day biochemical oxygen demand (BOD5) of 13.5 - 21.7 mg/L, and color of 58 - 76° were observed during the 20-day continuous operation. Outflows with average COD of 43 mg/L, BOD5 of 6.6 mg/L, and color of 5.6° were obtained after being decontaminated by the hybrid system with ozone dosage of 0.25 mg O3applied/mg COD0, 40 min ozonation contact time, 30 min hydraulic retention time (HRT) for AC treatment, and 2.5 h HRT for BAF treatment. More than 82 % of the genotoxicity of BTDW was eliminated in the ozonation unit. The genotoxicity of the BAF effluent was less than 1.33 μg 4-nitroquinoline-N-oxide/L. Ozonation could change the organics molecular structures, destroy chromophores, increase the biodegradability, and obviously reduce the genotoxicity of BTDW. Results showed that the combined process could guarantee water reuse with high quality.

  20. Combination of ozonation, activated carbon, and biological aerated filter for advanced treatment of dyeing wastewater for reuse.

    PubMed

    Zou, Xiao-Ling

    2015-06-01

    Laboratorial scale experiments were performed to investigate and evaluate the performance and removal characteristics of organics, color, and genotoxicity by an integrated process including ozonation, activated carbon (AC), and biological aerated filter (BAF) for recycling biotreated dyeing wastewater (BTDW) collected from a cotton textile factory. Influent chemical oxygen demand (COD) in the range of 156 - 252 mg/L, 5-day biochemical oxygen demand (BOD5) of 13.5 - 21.7 mg/L, and color of 58 - 76° were observed during the 20-day continuous operation. Outflows with average COD of 43 mg/L, BOD5 of 6.6 mg/L, and color of 5.6° were obtained after being decontaminated by the hybrid system with ozone dosage of 0.25 mg O3applied/mg COD0, 40 min ozonation contact time, 30 min hydraulic retention time (HRT) for AC treatment, and 2.5 h HRT for BAF treatment. More than 82 % of the genotoxicity of BTDW was eliminated in the ozonation unit. The genotoxicity of the BAF effluent was less than 1.33 μg 4-nitroquinoline-N-oxide/L. Ozonation could change the organics molecular structures, destroy chromophores, increase the biodegradability, and obviously reduce the genotoxicity of BTDW. Results showed that the combined process could guarantee water reuse with high quality. PMID:25843826

  1. Modulations of benzo[a]pyrene-induced DNA adduct, cyclin D1 and PCNA in oral tissue by 1,4-phenylenebis(methylene)selenocyanate

    SciTech Connect

    Chen, Kun-Ming; Sacks, Peter G.; Spratt, Thomas E.; Lin, Jyh-Ming; Boyiri, Telih; Schwartz, Joel; Richie, John P.; Calcagnotto, Ana; Das, Arunangshu; Bortner, James; Zhao, Zonglin; Amin, Shantu; Guttenplan, Joseph; El-Bayoumy, Karam

    2009-05-22

    Tobacco smoking is an important cause of human oral squamous cell carcinoma (SCC). Tobacco smoke contains multiple carcinogens include polycyclic aromatic hydrocarbons typified by benzo[a]pyrene (B[a]P). Surgery is the conventional treatment approach for SCC, but it remains imperfect. However, chemoprevention is a plausible strategy and we had previously demonstrated that 1,4-phenylenebis(methylene)selenocyanate (p-XSC) significantly inhibited tongue tumors-induced by the synthetic 4-nitroquinoline-N-oxide (not present in tobacco smoke). In this study, we demonstrated that p-XSC is capable of inhibiting B[a]P-DNA adduct formation, cell proliferation, cyclin D1 expression in human oral cells in vitro. In addition, we showed that dietary p-XSC inhibits B[a]P-DNA adduct formation, cell proliferation and cyclin D1 protein expression in the mouse tongue in vivo. The results of this study are encouraging to further evaluate the chemopreventive efficacy of p-XSC initially against B[a]P-induced tongue tumors in mice and ultimately in the clinic.

  2. Effects of mutagens on the clonal lifespan of Paramecium tetraurelia.

    PubMed

    Fukushima, S; Ogawa, H; Sasagawa, S

    1992-01-01

    There has been interest in the phenomenon that a cell cannot undergo unlimited reproduction under adequate conditions and undergoes senescence. In holotrichous ciliates, Paramecium has a limit of vegetative reproduction without sexual reproduction but Tetrahymena does not always have a limited lifespan. Comparing the two species would increase our knowledge of the mechanism of cellular clonal aging. We previously showed that mutations induced by X-rays shorten clonal lifespan. In this study, we examined whether mutagens shorten the clonal lifespan of Paramecium tetraurelia. P. tetraurelia was exposed to the alkylating agent N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), 0.045 mg/ml, for 30 min. The animal was exposed to MNNG 6 times in total while young (under 80 divisions from the start of a clonal life cycle) or 4 times during the senescent stage. MNNG shortened the clonal lifespan as expressed by the decrease in fission number from 186 +/- 55 (4 cell lines) to 136 +/- 21 (6 cell lines) with the first two treatments but with further exposures the lifespan increased to 182 +/- 15 (5 cell lines). MNNG had no effect when administered at the older age. Exposure of P. tetraurelia to 4-nitroquinoline-N-oxide at 0.021 mg/ml twice for 12 and 15 min at the younger age reduced the mean clonal lifespan from 143 +/- 28 to 125 +/- 21 and the maximum lifespan from 263 +/- 33 to 175 +/- 25. PMID:1372686

  3. Coupling cytotoxicity biomarkers with DNA damage assessment in TK6 human lymphoblast cells.

    PubMed

    Shi, Jing; Springer, Sandra; Escobar, Patricia

    2010-02-01

    There is considerable discussion within the scientific community as to the appropriate measures of cytotoxicity to use when deciding on the maximum concentration of a substance to test in vitro for its ability to induce DNA damage using the Comet assay. Conventional cytotoxicity assessment methods, such as trypan blue dye exclusion or relative cell number (cell counts) may not be the most biologically relevant measurement for cytotoxicity in this assay. Thus, we evaluated for decreased levels of adenosine triphosphate (ATP) and activation of Caspase-3/7 as well as relative cell number and trypan blue exclusion in order to understand the correlation among test compound concentration, cytotoxicity and genotoxicity outcomes in the Comet assay. We tested two non-genotoxic and non-cytotoxic compounds (d-glucose and ethanol), two non-genotoxic but cytotoxic compounds (2,4-dichlorophenol and tunicamycin) and four genotoxic and cytotoxic compounds (methyl methanesulfonate, ethyl methanesulfonate, etoposide and 4-nitroquinoline-N-oxide) in TK6 human lymphoblast cells. Our data show that measuring ATP and Caspase-3/7 levels provides more rapid and perhaps more biologically relevant measures of cytotoxicity compared with trypan blue dye exclusion and relative cell number. Furthermore, incorporating these two assays into the Comet assay also provided insight on the cytotoxic mode of action of the chemicals tested. By extrapolation, such assays may also be useful in other in vitro genotoxicity assays. PMID:20100597

  4. Inhibitory activity of cigarette-smoke condensate on the mutagenicity of heterocyclic amines.

    PubMed

    Lee, C K; Munoz, J A; Fulp, C; Chang, K M; Rogers, J C; Borgerding, M F; Doolittle, D J

    1994-07-01

    Cigarette-smoke condensate (CSC) is a complex mixture containing over 3800 identified chemicals including nicotine, water, mutagens, antimutagens, cytotoxins and inert chemicals. Although CSC is mutagenic in the Ames test, its effect on the activity of other mutagens has not been characterized. Using the Ames Salmonella bacterial mutagenesis assay, we found CSC exerts a significant inhibitory effect on mutagens requiring bioactivation. Those studied included heterocyclic amines (Glu-P-1, Glu-P-2, IQ, MeIQ, Trp-P-1 and Trp-P-2), benzo[a]pyrene (B[a]P) and aflatoxin B1. However, CSC had no effect on the activity of direct-acting mutagens (2-nitrofluorene, sodium azide, 4-nitro-1,2-phenylenediamine, 4-nitroquinoline N-oxide and methyl methanesulfonate). With indirect-acting mutagens, the reduced number of revertants observed in the presence of CSC was not attributable to cytotoxicity. CSC exhibited a potent inhibitory effect on the cytochrome P-450 dependent monooxygenases, ethoxyresorufin O-deethylase and B[a]P hydroxylase. This suggests inhibition of the cytochrome P-450 isozymes as one possible mechanism for the antimutagenicity of CSC. Fractionation studies of CSC revealed that the neutral, weakly acidic (phenolic) and basic fractions are all effective as antimutagens against Glu-P-1, a representative heterocyclic amine. This indicates that several classes of chemicals contribute to the inhibitory effect of CSC on the mutagenicity of the heterocyclic amines. PMID:7517501

  5. A new mutagenicity assay method for frameshift mutagens based on deleting or inserting a guanosine nucleotide in the beta-lactamase gene.

    PubMed

    Hour, T C; Lee, C C; Lin, J K

    1995-09-01

    The conventional method of site-directed mutagenesis was used to develop two Salmonella strains, JK-1 and JK-2, for detecting frameshift mutagens. The JK-1 strain was derived from Salmonella typhimurium TA1537 strain transformed by a mutant construct. A guanosine nucleotide was inserted between nucleotide residues 312 and 313 of the beta-lactamase gene. The JK-2 strain was obtained by the same procedure, but a guanosine nucleotide in position 315 of the beta-lactamase gene was deleted. The strains were tested with ten frameshift mutagens and the revertants were selected by ampicillin resistance. Representative mutagens including 2-nitrofluorene (2-NF), 2-acetylaminofluorene (AAF), 9-aminoacridine (9-AA), 2,7-diaminofluorene (2,7-DAF) and 2-methoxy-6-chloro-9-(3-(ethyl-2-chloro-ethyl)-aminopropylamino)acridine (ICR-170) were more potent in the JK-1 strain than the JK-2 strain, and the number of revertant colonies were dose related. Under the same conditions, the ampicillin test was more sensitive than the Ames test. Other types of compounds such as 2-methoxy-6-chloro-9-(2-chloroethylaminopropylamino)acridine (ICR-191), benzo[a]pyrene (BP), 4-nitroquinoline N-oxide (4-NQNO), hycanthone and aflatoxin B1 (AFB1) were not as mutagenic to these new strains. The method is quite promising for studying certain specific frameshift mutagens, but more chemical mutagens should be tested to validate its applicability and reproducibility in general use. PMID:8544757

  6. Phenobarbital: does the positive result in TA1535 indicate genotoxic properties?

    PubMed

    Albertini, S; Gocke, E

    1992-01-01

    The liver carcinogen phenobarbital (PB) causes a weak but reproducible increase of the mutant frequency in the Ames test, strain TA1535, without S9. Since there is no obvious chemical basis for a "DNA reactivity" of this compound experiments were performed to obtain information about possible indirect mechanisms of enhancing the number of spontaneous mutant colonies. In the course of the study strong synergistic and comutagenic effects of PB when given in combination with Na-azide or 2-aminoanthracene (2AA) were observed. Not only TA1535 but the complete set of tester strains was responsive. However, PB did not enhance the effects of other mutagens such as 4-nitroquinoline N-oxide or 2-nitrofluorene. It is argued that in strain TA1535 the fixation and expression of spontaneously occurring DNA lesions is amenable to modulation by PB similar to that of Na-azide or 2AA induced lesions. Thus in the usual sense, PB is not genotoxic in the Ames test. Methapyrilene, another liver carcinogen with an assumed nongenotoxic mode of action, showed almost identical properties in these experiments. PMID:1541257

  7. Analysis of the interlaboratory and intralaboratory reproducibility of the enhancement of simian adenovirus SA7 transformation of Syrian hamster embryo cells by model carcinogenic and noncarcinogenic compounds.

    PubMed

    Schechtman, L M; Hatch, G G; Anderson, T M; Putman, D L; Kouri, R E; Cameron, J W; Nims, R W; Spalding, J W; Tennant, R W; Lubet, R A

    1986-01-01

    The intralaboratory and interlaboratory reproducibility of a DNA virus (SA7) transformation enhancement assay was investigated using nine carcinogenic and noncarcinogenic compounds representing a variety of chemical classes. By the use of standardized procedures designed to limit assay variables, replicate assay data were collected in two independent laboratories and analyzed for concurrence. The carcinogens, 7,12-dimethylbenz(a)anthracene, benzo(a)pyrene, and N-methyl-N'-nitro-N-nitrosoguanidine yielded reproducible dose-dependent cytotoxicity and positive transformation effects (defined as statistically significant [p less than or equal to 0.05] enhancement of virus transformation at two or more consecutive dose levels) in all experiments in both laboratories. The carcinogens lead chromate, diethylnitrosamine, 4-nitroquinoline-N-oxide, and 2-acetylaminofluorene demonstrated enhancement of SA7 transformation at two or more dose levels in 40-50% of the assays. The noncarcinogenic structural analogs anthracene and pyrene consistently did not produce positive assay responses when tested at dose levels up to the limits of solubility. Good interlaboratory concurrence was demonstrated for these model compounds in the Syrian hamster embryo cell-SA7 assay. PMID:3089771

  8. Mutagenicity of fine airborne particles: diurnal variation in community air determined by a Salmonella micro preincubation (microsuspension) procedure

    SciTech Connect

    Kado, N.Y.; Guirguis, G.N.; Flessel, C.P.; Chan, R.C.; Chang, K.I.; Wesolowski, J.J.

    1986-01-01

    A simple modification of the Salmonella liquid incubation assay previously developed for detecting mutagens in urine was used to determine mutagenic activity of airborne particulate matter. The modification consists of adding ten times more bacteria and five to ten times less metabolic enzymes compared to the plate incorporation method. The mixture volume is approximately 0.2 ml, and the mixture is incubated for 90 min before pouring it according to the standard protocol. The modified procedure was approximately ten times more sensitive than the standard plate incorporation test for detecting mutagens in air particulate extracts and approximately ten to 31 times more sensitive for the chemical mutagens 2-nitrofluorene, 4-nitroquinoline-N-oxide, 2-aminofluorene, and benzo(a)pyrene in bacterial strain TA98. Mutagenic activity was associated exclusively with fine particles (aerodynamic diameters of less than 2.5 ..mu..m). Diurnal patterns of mutagenic activity were investigated by measuring filter extracts from 2-hr samples collected in three San Francisco Bay Area cities during the summer or fall of 1982. Four criteria pollutants - lead, nitrogen dioxide, ozone, and sulfur dioxide - were simultaneously sampled at one location.

  9. Green tea and skin--anticarcinogenic effects.

    PubMed

    Mukhtar, H; Katiyar, S K; Agarwal, R

    1994-01-01

    Because of its special aroma, green tea is a popular beverage consumed by some human populations worldwide. In recent years, many laboratory studies have shown that in a variety of animal tumor bioassay systems the administration of green tea, specifically the polyphenolic fraction isolated from green tea leaves (green tea polyphenols), affords protection against cancer induction. In mouse skin tumor bioassay systems, topical application of green tea polyphenols to skin has been shown to result in protection against a) 3-methylcholanthrene-induced skin tumorigenicity, b) 7,12-dimethylbenz(a)anthracene (DMBA)-induced skin tumor initiation, c) 12-O-tetradecanoylphorbol-13-acetate and other tumor promoters caused tumor promotion in DMBA-initiated skin, and d) benzoyl peroxide- and 4-nitroquinoline N-oxide caused enhanced malignant progression of nonmalignant lesions. Green tea extract has also been shown to cause partial regression of established skin papillomas in mouse. Similarly, chronic oral feeding of green tea polyphenols or water extract of green tea has also been shown to result in the protection against both chemical carcinogen- and ultraviolet B radiation-induced skin tumorigenicity. Collectively these data suggest that green tea possesses significant chemopreventive effect against each stage of carcinogenesis, and that it may be useful against inflammatory responses associated with the exposure of skin to chemical tumor promoters as well as to solar radiation. Available data regarding the mechanism by which green tea affords these diversified effects is discussed.

  10. Protective effects of five allium derived organosulfur compounds against mutation and oxidation.

    PubMed

    Chiu, Chih-Kwang; Chen, Tai-Yuan; Lin, Jou-Hsing; Wang, Chen-Ya; Wang, Bor-Sen

    2016-04-15

    In this study, we examined the ability of five allium-derived organosulfur compounds to protect cells against mutation and oxidation. The compounds tested were 1-propylmercaptan (PM), dimethyl disulfide (DMDS), diallyl disulfide (DADS), propyl disulfide (PDS), and 2,5-dimethylthiophene (DMT). Our results showed that when used at concentrations of 100-400 μmol/l, the five compounds inhibited the mutagenicity of 4-nitroquinoline-N-oxide, a direct mutagen, and benzo[a]pyrene, an indirect mutagen, toward Salmonella typhimurium TA 98 and TA 100. Furthermore, at these concentrations, all five of the compounds protected HepG2 cells against tert-butyl hydroperoxide-induced oxidative cytotoxicity. The compounds likely enhanced cell viability by suppressing the formation of reactive oxygen species and the depletion of glutathione depletion in cells. DMT and PM inhibited mutation and oxidation to a greater extent than DMDS, DADS, and PDS. These results demonstrate for the first time that DMT and PM can contribute to the antimutagenic and the antioxidative property of Allium vegetables. PMID:26617023

  11. Mutagen sensitivity as measured by induced chromatid breakage as a marker of cancer risk.

    PubMed

    Wu, Xifeng; Zheng, Yun-Ling; Hsu, T C

    2014-01-01

    Risk assessment is now recognized as a multidisciplinary process, extending beyond the scope of traditional epidemiologic methodology to include biological evaluation of interindividual differences in carcinogenic susceptibility. Modulation of environmental exposures by host genetic factors may explain much of the observed interindividual variation in susceptibility to carcinogenesis. These genetic factors include, but are not limited to, carcinogen metabolism and DNA repair capacity. This chapter describes a standardized method for the functional assessment of mutagen sensitivity. This in vitro assay measures the frequency of mutagen-induced breaks in the chromosomes of peripheral blood lymphocytes. Mutagen sensitivity assessed by this method has been shown to be a significant risk factor for tobacco-related maladies, especially those of the upper aerodigestive tract. Mutagen sensitivity may therefore be a useful member of a panel of susceptibility markers for defining high-risk subgroups for chemoprevention trials. This chapter describes methods for and discusses results from studies of mutagen sensitivity as measured by quantifying chromatid breaks induced by clastogenic agents, such as the γ-radiation mimetic DNA cross-linking agent bleomycin and chemicals that form so-called bulky DNA adducts, such as 4-nitroquinoline and the tobacco smoke constituent benzo[a]pyrene, in short-term cultured peripheral blood lymphocytes.

  12. DNA repair and chromosome aberrations: the effect of cytosine arabinoside on the frequency of chromosome aberrations induced by radiation and chemicals

    SciTech Connect

    Preston, R.J.

    1980-01-01

    The frequency of x-ray-induced chromosome aberrations in G0 human lymphocytes was greatly increased when cells were incubated with cytosine arabinoside (ara-C) after irradiation. The frequency of dicentrics increased with increasing ara-C incubation times (one, two, and three hours). Lymphocytes from Down syndrome individuals were more sensitive to aberration induction by x-rays in G0, and the increase in dicentric frequency with ara-C incubation was much more rapid than with normal cells. When G2 normal lymphocytes were x-irradiated and incubated for two or three hours with ara-C until fixation, there was a large increase in deletion frequency compared to cells x-irradiated and incubated in the absence of ara-C. However, no exchanges were observed in the presence of ara-C, compared to 0.29 per cell as when x-rays alone were given. These results form the basis for a discussion of the mechanism of aberration induction by x-rays. Experiments with two chemicals, 4-nitroquinoline-N-oxide and methyl methanesulfonate, show that chromosome-type aberrations can be induced in G1 treated lymphocytes incubated with ara-C. However, these chemicals, in the absence of ara-C incubation, induced no aberrations in G1 at the concentrations used. The mechanism of aberration induction is discussed, particularly in terms of whether or not chemicals can be defined as S-phase dependent.

  13. Crystal structures of 2,3-bis­(4-chloro­phen­yl)-1,3-thia­zolidin-4-one and trans-2,3-bis­(4-chloro­phen­yl)-1,3-thia­zolidin-4-one 1-oxide

    PubMed Central

    Yennawar, Hemant P.; Tierney, John; Hullihen, Patrick D.; Silverberg, Lee J.

    2015-01-01

    In the crystal structures of the title compounds, C15H11Cl2NOS, (1), and C15H11Cl2NO2S, (2), wherein (2) is the oxidized form of (1), the thia­zolidine ring is attached to two chloro­phenyl rings. The chloro­phenyl ring on the 2-carbon atom position points in the same direction as that of the S atom in (1), while in (2), the S atom points in the opposite direction. The O atom on the chiral S atom in (2) is trans to the chloro­phenyl ring on the 2-carbon. The chloro­phenyl ring planes in each structure are close to orthogonal, making dihedral angles of 78.61 (6) and 87.46 (8)° in (1) and (2), respectively. The thia­zolidine ring has a twisted conformation on the S—Cmethine bond in (1), and an envelope conformation with the S atom 0.715 (3) Å out of the plane of other four atoms in (2). In the crystal of (1), mol­ecules are linked by C—H⋯O hydrogen bonds, as well as by slipped parallel π–π inter­actions [inter-centroid distance = 3.840 (3) Å] between inversion-related phenyl rings, forming sheets parallel to (001). In the crystal of (2), mol­ecules are linked via C—H⋯O and C—H⋯Cl hydrogen bonds, forming slabs parallel to (001). PMID:25844183

  14. Dinitro derivatives of pyrene and fluoranthene in diesel emission particulates and their tumorigenicity in mice and rats.

    PubMed

    Tokiwa, H; Otofuji, T; Nakagawa, R; Horikawa, K; Maeda, T; Sano, N; Izumi, K; Otsuka, H

    1986-01-01

    A number of mutagens/carcinogens in diesel emission particulates are produced and distributed into the atmosphere. On the basis of the results of chemical analysis, it was found that most of the mutagenicity in diesel particulate extracts is due to super-mutagens such as 1,3-, 1,6- and 1,8-DNP, and 3,7- and 3,9-DNF. 3,7- and 3,9-DNF are new mutagens which were isolated in this study and they induced a frameshift type mutation in the Salmonella microsome test. Each derivative of DNP and DNF was detected at a concentration of 0.01 to 0.03 ppm in the particulates while the diesel engine was used under the condition of idling. 1,6- and 1,8-DNP were tumorigenic at the injection site in BALB/c male mice when a total of 2 and 1 mg, respectively, of the compounds was given subcutaneously. The incidences for tumors by 60 weeks were at a ratio of 50 and 30%, respectively, for 1,6- and 1,8-DNP-treated mice. 4-NQO and BaP, as positive control, induced tumors at the injection site in BALB/c mice when a total of 2 and 1 mg, respectively, of the compound was given. The incidences of tumors were observed at a high ratio of 90 and 93.4%, respectively, for 4-NQO- and BaP-treated mice. Histologically the tumors were diagnosed as malignant fibrous histiocytomas in all the tumors which developed. No tumors occurred at the injection site in mice given injections of 1,3-DNP. Tumorigenicity tests of 3,7- and 3,9-DNF are now being attempted using F344/DuCrj male rats. This animal experiment is now in progress. In the 3,9-DNF-treated rats (a total of 1 mg per rat), subcutaneous tumors developed in 8 of 11 rats up to 150 days after injection, and a part of a tumor resected from a rat showed the typical features of rhabdomyosarcoma.

  15. Sources of variability in Ames Salmonella typhimurium tester strains: analysis of the International Collaborative Study on 'genetic drift'.

    PubMed

    Margolin, B H; Risko, K J; Shelby, M D; Zeiger, E

    1984-02-01

    Data from 38 laboratories using 5 strains of Salmonella typhimurium (TA98, TA100, TA1535, TA1537, and TA1538) were analyzed to determine sources and magnitudes of test data variability. Each laboratory tested the mutagenicity of 4-nitroquinoline-N-oxide by the same protocol, using both its in-house cultures and a set of reference cultures provided to all laboratories. It was found that neither plate-to-plate nor day-to-day variability within a laboratory differed substantially between the in-house and reference cultures for any strain; this indicated no difference in the laboratories' handling of the two cultures. Not surprisingly, on average, plate-to-plate variability was substantially smaller than day-to-day variability within a laboratory, which, in turn, was substantially smaller than inter-laboratory variability. The solvent DMSO was found to have a small (6-7%) but statistically significant depressive effect on the spontaneous mutant frequency for the two plasmid-containing strains, TA98 and TA100, but not for the other three strains. When the mean value and variance of all laboratories for the in-house culture were compared with the corresponding reference culture values for each dose and strain, no major differences were seen. Any increase in mean or variance in the distribution of laboratory means in one of the two cultures could be ascribed largely to a small number of laboratories. Laboratories that reported 'high' or 'low' levels of spontaneous or induced revertants per plate tended to deviate in the same direction for most strains and for both in-house and reference cultures. If 'genetic drift' contributed to the inter-laboratory variability in this collaborative study, it was a minor component that went undetected in our analyses.

  16. Genotoxicity of Heterocyclic PAHs in the Micronucleus Assay with the Fish Liver Cell Line RTL-W1

    PubMed Central

    Brinkmann, Markus; Blenkle, Henning; Salowsky, Helena; Bluhm, Kerstin; Schiwy, Sabrina; Tiehm, Andreas; Hollert, Henner

    2014-01-01

    Heterocyclic aromatic hydrocarbons are, together with their un-substituted analogues, widely distributed throughout all environmental compartments. While fate and effects of homocyclic PAHs are well-understood, there are still data gaps concerning the ecotoxicology of heterocyclic PAHs: Only few publications are available investigating these substances using in vitro bioassays. Here, we present a study focusing on the identification and quantification of clastogenic and aneugenic effects in the micronucleus assay with the fish liver cell line RTL-W1 that was originally derived from rainbow trout (Oncorhynchus mykiss). Real concentrations of the test items after incubation without cells were determined to assess chemical losses due to, e.g., sorption or volatilization, by means of gas chromatography-mass spectrometry. We were able to show genotoxic effects for six compounds that have not been reported in vertebrate systems before. Out of the tested substances, 2,3-dimethylbenzofuran, benzothiophene, quinoline and 6-methylquinoline did not cause substantial induction of micronuclei in the cell line. Acridine caused the highest absolute induction. Carbazole, acridine and dibenzothiophene were the most potent substances compared with 4-nitroquinoline oxide, a well characterized genotoxicant with high potency used as standard. Dibenzofuran was positive in our investigation and tested negative before in a mammalian system. Chemical losses during incubation ranged from 29.3% (acridine) to 91.7% (benzofuran) and may be a confounding factor in studies without chemical analyses, leading to an underestimation of the real potency. The relative potency of the investigated substances was high compared with their un-substituted PAH analogues, only the latter being typically monitored as priority or indicator pollutants. Hetero-PAHs are widely distributed in the environment and even more mobile, e.g. in ground water, than homocyclic PAHs due to the higher water solubility. We

  17. A pilot survey of 39 Victorian WWTP effluents using a high speed luminescent umu test in conjunction with a novel GC-MS-database technique for automatic identification of micropollutants.

    PubMed

    Allinson, Mayumi; Kageyama, Shiho; Nakajima, Daisuke; Kamata, Ryo; Shiraishi, Fujio; Goto, Sumio; Salzman, Scott Andrew; Allinson, Graeme

    2012-01-01

    In 2007, samples of treated effluent were collected at point of discharge to the environment from 39 wastewater treatment plants (WWTPs) located across Victoria, Australia grouped by treatment type. Sample genotoxicity was assessed with a high-throughput luminescent umu test method using Salmonella typhimurium TL210 strain, with and without addition of a commercially available metabolic activation system. Samples were also screened using a gas chromatographic-mass spectrometric mass-structure database recognition method. A genotoxic response was observed in half of the samples tested without metabolic activation system (4-nitroquinoline-N-oxide equivalents). On addition of metabolic activation system, 75% of samples elicited a genotoxic response, the majority of responses were stronger than without metabolic activation (

  18. Comet assay with the fish cell line rainbow trout gonad-2 for in vitro genotoxicity testing of xenobiotics and surface waters.

    PubMed

    Nehls, Sebastian; Segner, Helmut

    2005-08-01

    The present study examines the potential of the comet assay using the rainbow trout gonad cell line-2 (RTG-2) as an in vitro indicator test for genotoxicity assessment of aquatic contaminants and native surface waters. Initially, the comet assay protocol was adapted to the RTG-2 cell line. An exposure period of 2 h was found to be optimal, because DNA damage decreased when exposure was prolonged. Then, the sensitivity of the comet assay with RTG-2 cells toward six genotoxic reference substances was evaluated. The lowest-observed-effect concentration values for the directly acting genotoxins, 4-nitroquinoline-N-oxide and N-methyl-N'-nitro-N-nitrosoguanidine, were in the low nanomolar range. The RTG-2 test system clearly was less sensitive for the indirectly acting genotoxins benzo[a]pyrene, nitrofurantoin, 2-acetylaminofluorene, and dimethylnitrosamine, despite the presence of xenobiotic metabolic capacities in RTG-2 cells. The two effect endpoints used, tail length (TL) and tail moment (TM), did not differ with respect to sensitivity, but the linearity of the concentration-response curve was better with TM than with TL. The overall reproducibility of the assay results was good. Finally, the applicability of the comet assay with RTG-2 cells for genotoxicity screening of native surface water samples was studied. The assay tolerated the use of nonsterile water samples and was able to detect genotoxic potentials in native water samples; that is, extraction and concentration of the samples were not needed. The results of the present study indicate the suitability of the comet assay with the fish cell line, RTG-2, as in vitro screen for detecting genotoxic potencies of xenobiotics and environmental samples.

  19. The Candida albicans CDR3 gene codes for an opaque-phase ABC transporter.

    PubMed Central

    Balan, I; Alarco, A M; Raymond, M

    1997-01-01

    We report the cloning and functional analysis of a third member of the CDR gene family in Candida albicans, named CDR3. This gene codes for an ABC (ATP-binding cassette) transporter of 1,501 amino acids highly homologous to Cdr1p and Cdr2p (56 and 55% amino acid sequence identity, respectively), two transporters involved in fluconazole resistance in C. albicans. The predicted structure of Cdr3p is typical of the PDR/CDR family, with two similar halves, each comprising an N-terminal hydrophilic domain with consensus sequences for ATP binding and a C-terminal hydrophobic domain with six predicted transmembrane segments. Northern analysis showed that CDR3 expression is regulated in a cell-type-specific manner, with low levels of CDR3 mRNA in CAI4 yeast and hyphal cells, high levels in WO-1 opaque cells, and undetectable levels in WO-1 white cells. Disruption of both alleles of CDR3 in CAI4 resulted in no obvious changes in cell morphology, growth rate, or susceptibility to fluconazole. Overexpression of Cdr3p in C. albicans did not result in increased cellular resistance to fluconazole, cycloheximide, and 4-nitroquinoline-N-oxide, which are known substrates for different transporters of the PDR/CDR family. These results indicate that despite a high degree of sequence conservation with C. albicans Cdr1p and Cdr2p, Cdr3p does not appear to be involved in drug resistance, at least to the compounds tested which include the clinically relevant antifungal agent fluconazole. Rather, the high level of Cdr3p expression in WO-1 opaque cells suggests an opaque-phase-associated biological function which remains to be identified. PMID:9393682

  20. Mutagenicity of fine (less than 2. 5 microns) airborne particles: diurnal variation in community air determined by a Salmonella micro preincubation (microsuspension) procedure

    SciTech Connect

    Kado, N.Y.; Guirguis, G.N.; Flessel, C.P.; Chan, R.C.; Chang, K.I.; Wesolowski, J.J.

    1986-01-01

    A simple modification of the Salmonella liquid incubation assay previously developed for detecting mutagens in urine was used to determine mutagenic activity of airborne particulate matter. The modification consists of adding ten times more bacteria (approximately 10(9) per incubation tube) and five to ten times less metabolic enzymes compared to the plate incorporation method. The mixture volume is approximately 0.2 ml, and the mixture is incubated for 90 min before pouring it according to the standard protocol. The modified procedure (micro preincubation or microsuspension) was approximately ten times more sensitive than the standard plate incorporation test for detecting mutagens in air particulate extracts and approximately ten to 31 times more sensitive for the chemical mutagens 2-nitrofluorene, 4-nitroquinoline-N-oxide, 2-aminofluorene, and benzo(a)pyrene in bacterial strain TA98. Mutagenic activity was detected in particle extracts obtained from 1 m3 of air (17 micrograms of extract) or less. This microsuspension procedure was applied to air particulate samples collected with low-volume (15-50 liters per min) virtual-dichotomous air samplers. Mutagenic activity was associated exclusively with fine particles (aerodynamic diameters of less than 2.5 microns). Diurnal patterns of mutagenic activity (TA98 revertants per cubic meter air) were investigated by measuring filter extracts from 2-hr samples collected in three San Francisco Bay Area cities during the summer or fall of 1982. Four criteria pollutants--lead, nitrogen dioxide, ozone, and sulfur dioxide--were simultaneously sampled at one location. Mutagenicity from fine particles sampled at this location was highly correlated with lead and much less correlated with nitrogen dioxide, ozone, and sulfur dioxide. The microsuspension procedure is applicable in testing samples of limited mass.

  1. A Synthetic Interaction between CDC20 and RAD4 in Saccharomyces cerevisiae upon UV Irradiation

    PubMed Central

    Rochelle, Lauren; Roberts, Asela

    2014-01-01

    Regulation of DNA repair can be achieved through ubiquitin-mediated degradation of transiently induced proteins. In Saccharomyces cerevisiae, Rad4 is involved in damage recognition during nucleotide excision repair (NER) and, in conjunction with Rad23, recruits other proteins to the site of damage. We identified a synthetic interaction upon UV exposure between Rad4 and Cdc20, a protein that modulates the activity of the anaphase promoting complex (APC/C), a multisubunit E3 ubiquitin ligase complex. The moderately UV sensitive Δrad4 strain became highly sensitive when cdc20-1 was present, and was rescued by overexpression of CDC20. The double mutant is also deficient in elicting RNR3-lacZ transcription upon exposure to UV irradiation or 4-NQO compared with the Δrad4 single mutant. We demonstrate that the Δrad4/cdc20-1 double mutant is defective in double strand break repair by way of a plasmid end-joining assay, indicating that Rad4 acts to ensure that damaged DNA is repaired via a Cdc20-mediated mechanism. This study is the first to present evidence that Cdc20 may play a role in the degradation of proteins involved in nucleotide excision repair. PMID:24707403

  2. Suppression of SOS response in E. coli PQ 37, antioxidant potential and antiproliferative action of methanolic extract of Pteris vittata L. on human MCF-7 breast cancer cells.

    PubMed

    Kaur, Paramjeet; Kaur, Varinder; Kumar, Manish; Kaur, Satwinderjeet

    2014-12-01

    Pteris vittata L. from the foothills of Kangra district, Himachal Pradesh, India has been investigated for its potential to combat reactive oxygen species and DNA damaging agents. DPPH radical, superoxide anion radical, ABTS(+.) radical cation decolorization, reducing power, deoxyribose degradation, plasmid nicking and lipid peroxidation assays were carried out to evaluate the antioxidant potential of methanolic of P. vittata L. (PME). The extract showed a significant potential in scavenging the free radicals and an IC50 of 64.425 µg/ml and 90.143 µg/ml was obtained in superoxide radical scavenging and reducing power assays respectively. PME inhibited lipid peroxidation with an IC50 of 34.35 µg/ml and protected the plasmid DNA from damage by hydroxyl radicals to varying degrees. Percentage inhibition of 81.22 and 89.36 at a concentration of 160 µg/ml was obtained in non site specific and site specific deoxyribose degradation assays respectively. PME significantly inhibited 4NQO induced mutagenicity in Escherichia coli PQ 37 and a decrease in induction factor was observed with increasing concentration. The amount of total phenolic and flavonoid content were also determined and HPLC analysis was carried out for the identification of phytoconstituents. A dose dependent decrease in viability of MCF-7 cells was observed with GI50 value of 153.967 µg/ml.

  3. Indomethacin Treatment of Mice with Premalignant Oral Lesions Sustains Cytokine Production and Slows Progression to Cancer

    PubMed Central

    Johnson, Sara D.; Young, M. Rita I.

    2016-01-01

    Current treatment options for head and neck squamous cell carcinoma (HNSCC) patients are often ineffective due to tumor-localized and systemic immunosuppression. Using the 4-NQO mouse model of oral carcinogenesis, this study showed that premalignant oral lesion cells produce higher levels of the immune modulator, PGE2, compared to HNSCC cells. Inhibiting prostaglandin production of premalignant lesion cells with the pan-cyclooxygenase inhibitor indomethacin stimulated their induction of spleen cell cytokine production. In contrast, inhibiting HNSCC prostaglandin production did not stimulate their induction of spleen cell cytokine production. Treatment of mice bearing premalignant oral lesions with indomethacin slowed progression of premalignant oral lesions to HNSCC. Flow cytometric analysis of T cells in the regional lymph nodes of lesion-bearing mice receiving indomethacin treatment showed an increase in lymph node cellularity and in the absolute number of CD8+ T cells expressing IFN-γ compared to levels in lesion-bearing mice receiving diluent control treatment. The cytokine-stimulatory effect of indomethacin treatment was not localized to regional lymph nodes but was also seen in the spleen of mice with premalignant oral lesions. Together, these data suggest that inhibiting prostaglandin production at the premalignant lesion stage boosts immune capability and improves clinical outcomes. PMID:27713748

  4. Formation potentials of typical disinfection byproducts and changes of genotoxicity for chlorinated tertiary effluent pretreated by ozone.

    PubMed

    Cao, Nan; Miao, Tingting; Li, Kuixiao; Zhang, Yu; Yang, Min

    2009-01-01

    The effects of ozonation on the formation potential of typical disinfection byproducts (DBPs) and the changes of genotoxicity during post chlorination of tertiary effluent from a sewage treatment plant were investigated. Ozonation enhanced the yields of all detected chlorine DBPs except CHCl3. At a chlorine dose of 5 mg/L, the three brominated THMs and five HAAs increased, while chloroform decreased with the increase of ozone dose from 0 to 10 mg/L (ozone dose in consumption base). At a chlorine dose of 10 mg/L, the two mixed bromochloro species THMs and two dominant HAAs (DCAA and TCAA) increased firstly and then decreased with the increase of ozone dose, with the turning point approximately occurring at an ozone dose of 5 mg/L. The genotoxicity detected using umu test, on the other hand, was removed from 7 microg 4-NQO/L to a negligible level by ozonation under an ozone dose of 5 mg/L. Chlorination could further remove the genotoxicity to some extent. It was found that SUVA (UV absorbance divided by DOC concentration) might be used as an indicative parameter for monitoring the removal of genotoxicity during the oxidation.

  5. The histone demethylase LSD1 is a novel oncogene and therapeutic target in oral cancer.

    PubMed

    Wang, Yanling; Zhu, Yumin; Wang, Qiong; Hu, Huijun; Li, Zhongwu; Wang, Dongmiao; Zhang, Wei; Qi, Bin; Ye, Jinhai; Wu, Heming; Jiang, Hongbing; Liu, Laikui; Yang, Jianrong; Cheng, Jie

    2016-04-28

    The histone demethylase LSD1 functions as a key pro-oncogene and attractive therapeutic target in human cancer. Here we sought to interrogate the oncogenic roles of LSD1 in OSCC tumorigenesis and therapeutic intervention by integrating chemical-induced OSCC model, genetic and pharmacological loss-of-function approaches. Our data revealed that aberrant LSD1 overexpression in OSCC was significantly associated with tumor aggressiveness and shorter overall survival. Increased abundance of LSD1 was detected along with disease progression in DMBA- or 4NQO-induced OSCC animal models. LSD1 depletion via siRNA-mediated knockdown in OSCC cells resulted in impaired cell proliferation, migration/invasion, tumorsphere formation and reduced xenograft growth while inducing cell apoptosis and enhancing chemosensitivity to 5-FU. Moreover, treatments of LSD1 chemical inhibitors (pargyline and tranylcypromine) induced its protein reduction probably via enhanced protein degradation and produced similar phenotypic changes resembling LSD1 silencing in OSCC cells. Pharmacological inhibition of LSD1 by intraperitoneal delivery of these inhibitors resulted in impaired xenograft overgrowth. Taken together, our data reveal the tumorigenic roles of LSD1 and identified LSD1 as a novel biomarker with diagnostic and prognostic significance, and also establish that targeting LSD1 by chemical inhibitors is a viable therapeutic strategy against OSCC. PMID:26872725

  6. Changes in the components and biotoxicity of dissolved organic matter in a municipal wastewater reclamation reverse osmosis system.

    PubMed

    Sun, Ying-Xue; Hu, Hong-Ying; Shi, Chun-Zhen; Yang, Zhe; Tang, Fang

    2016-09-01

    The characteristics of dissolved organic matter (DOM) and the biotoxicity of these components were investigated in a municipal wastewater reclamation reverse osmosis (mWRRO) system with a microfiltration (MF) pretreatment unit. The MF pretreatment step had little effect on the levels of dissolved organic carbon (DOC) in the secondary effluent, but the addition of chlorine before MF promoted the formation of organics with anti-estrogenic activity. The distribution of excitation emission matrix (EEM) fluorescence constituents exhibited obvious discrepancies between the secondary effluent and the reverse osmosis (RO) concentrate. Using size exclusion chromatography, DOM with low molecular weights of approximately 1.2 and 0.98 kDa was newly formed during the mWRRO. The normalized genotoxicity and anti-estrogenic activity of the RO concentrate were 32.1 ± 10.2 μg4-NQO/mgDOC and 0.36 ± 0.08 mgTAM/mgDOC, respectively, and these values were clearly higher than those of the secondary effluent and MF permeate. The florescence volume of Regions I and II in the EEM spectrum could be suggested as a surrogate for assessing the genotoxicity and anti-estrogenic activity of the RO concentrate. PMID:26803912

  7. Ultraviolet light photobiology of the protozoan Tetrahymena pyriformis and chemical reactivation of DNA damage

    SciTech Connect

    Wheeler, J.S.

    1988-01-01

    The tunable dye laser was developed in order to perform UV-B and UV-C (254-320 nm) action spectra studies on several different organisms. Using the laser, action spectra studies have been performed for Escherichia coli, Saccharomyces, Chlamydomonas, Caenorhabditis elegans, Paramecium, and Tetrahymena pyriformis. Studies generally indicate increasing LD{sub 50} values with increasing wavelength. Two notable findings were made: (1) The action spectra does not follow the DNA absorption spectra at 280, 290 and 295 nm; (2) The repair competent/repair defective sensitization factor does not remain constant throughout the wavelength region. In addition it was found that the repair defective strain of E. coli, Bs-1, showed an increase in survival with increasing UV irradiation, at certain dose levels. Further experiments were designed to better characterize the reactivation. Tetrahymena were exposed to UV-C and reactivated with methyl methanesulfonate (MMS) and 4-nitro quinoline oxide (4-NQO). In both cases survival was seen to increase after chemical exposure. Likewise, UV-C was found to reactivate chemical damage (MMS).

  8. Changes in the components and biotoxicity of dissolved organic matter in a municipal wastewater reclamation reverse osmosis system.

    PubMed

    Sun, Ying-Xue; Hu, Hong-Ying; Shi, Chun-Zhen; Yang, Zhe; Tang, Fang

    2016-09-01

    The characteristics of dissolved organic matter (DOM) and the biotoxicity of these components were investigated in a municipal wastewater reclamation reverse osmosis (mWRRO) system with a microfiltration (MF) pretreatment unit. The MF pretreatment step had little effect on the levels of dissolved organic carbon (DOC) in the secondary effluent, but the addition of chlorine before MF promoted the formation of organics with anti-estrogenic activity. The distribution of excitation emission matrix (EEM) fluorescence constituents exhibited obvious discrepancies between the secondary effluent and the reverse osmosis (RO) concentrate. Using size exclusion chromatography, DOM with low molecular weights of approximately 1.2 and 0.98 kDa was newly formed during the mWRRO. The normalized genotoxicity and anti-estrogenic activity of the RO concentrate were 32.1 ± 10.2 μg4-NQO/mgDOC and 0.36 ± 0.08 mgTAM/mgDOC, respectively, and these values were clearly higher than those of the secondary effluent and MF permeate. The florescence volume of Regions I and II in the EEM spectrum could be suggested as a surrogate for assessing the genotoxicity and anti-estrogenic activity of the RO concentrate.

  9. Desmutagenicity of Melanoidins against Various Kinds of Mutagens and Activated Mutagens.

    PubMed

    Lee, I E; Chuyen, N V; Hayase, F; Kato, H

    1994-01-01

    The desmutagenic activities of low-molecular weight melanoidins (LM-MEL, MW 500-1000) and nondialyzable melanoidins (ND-MEL, MW above 1000) prepared from a glucose-glycine reaction system were examined by Ames' test on such mutagens/carcinogens as nitro or amino compounds of aromatics or heterocycles, azo compounds, nitroso compounds, and epoxides. ND-MEL and LM-MEL exhibited a desmutagenic activity of 25-75% against mutagenic aromatic or heterocyclic compounds such as aflatoxin B1, B[α]P, 2-aminofluorene, 4-aminobiphenyl, and 2-aminonaphthalene, as well as heterocyclic amines, using S. typhimurium TA98 in the presence of S9 mix. In the case of using S. typhimurium TA100 in the absence of S9 mix, ND-MEL and LM-MEL showed a desmutagenic activity of 20-50% against 2-nitrofluorene, 4NQO and 2-nitronaphthalene. The strong desmutagenic activity of MEL from various kinds of amino acids, peptides, or egg albumin hydrolyzates with glucose was also observed against Trp-P-1. Furthermore, MEL had marked desmutagenic activity against the Trp-P-1 activated by S9 mix and synthetic N-OH-Trp-P-2. PMID:27315699

  10. A miniaturized Ames mutagenicity assay employing bioluminescent strains of Salmonella typhimurium.

    PubMed

    Côté, C; Blaise, C; Delisle, C E; Meighen, E A; Hansen, P D

    1995-12-01

    Increased awareness of the role of environmental factors in carcinogenesis has led to an emphasis on preventing or minimizing exposure to genotoxicants. This is presently promoting the development of simple, rapid, cost-effective mutagenicity screening assays. We have developed a test system based on the well-known Salmonella mutagenicity assay. The lux genes, which permit cells to emit light through bioluminescence, were introduced into Salmonella typhimurium strain TA98. These bacteria were exposed for 48 h to chemicals or complex mixtures in 48-well microplates containing an appropriate liquid medium. Cells were subsequently centrifuged and resuspended in buffer. The final postexposure revertant biomass was then estimated using a microluminometer. Replication trials confirmed methodological reproducibility. Clear dose-response relationships were obtained with the direct frameshift mutagens 4NQO and 2NF. Mutagenicity threshold effect concentrations found for these compounds were comparable to those reported in the literature. Industrial effluents and environmental extracts (effluents, suspended solids) were also tested and results compared well with those of the SOS Chromotest. While further validation of this new adaptation of the Ames test will be required, it appears at this time that it could be well suited for routine screening of xenobiotics and environmental samples. PMID:8552135

  11. Bioanalytical tools for the evaluation of organic micropollutants during sewage treatment, water recycling and drinking water generation.

    PubMed

    Macova, Miroslava; Toze, Simon; Hodgers, Leonie; Mueller, Jochen F; Bartkow, Michael; Escher, Beate I

    2011-08-01

    A bioanalytical test battery was used for monitoring organic micropollutants across an indirect potable reuse scheme testing sites across the complete water cycle from sewage to drinking water to assess the efficacy of different treatment barriers. The indirect potable reuse scheme consists of seven treatment barriers: (1) source control, (2) wastewater treatment plant, (3) microfiltration, (4) reverse osmosis, (5) advanced oxidation, (6) natural environment in a reservoir and (7) drinking water treatment plant. Bioanalytical results provide complementary information to chemical analysis on the sum of micropollutants acting together in mixtures. Six endpoints targeting the groups of chemicals with modes of toxic action of particular relevance for human and environmental health were included in the evaluation: genotoxicity, estrogenicity (endocrine disruption), neurotoxicity, phytotoxicity, dioxin-like activity and non-specific cell toxicity. The toxicity of water samples was expressed as toxic equivalent concentrations (TEQ), a measure that translates the effect of the mixtures of unknown and potentially unidentified chemicals in a water sample to the effect that a known reference compound would cause. For each bioassay a different representative reference compound was selected. In this study, the TEQ concept was applied for the first time to the umuC test indicative of genotoxicity using 4-nitroquinoline as the reference compound for direct genotoxicity and benzo[a]pyrene for genotoxicity after metabolic activation. The TEQ were observed to decrease across the seven treatment barriers in all six selected bioassays. Each bioassay showed a differentiated picture representative for a different group of chemicals and their mixture effect. The TEQ of the samples across the seven barriers were in the same order of magnitude as seen during previous individual studies in wastewater and advanced water treatment plants and reservoirs. For the first time a benchmarking was

  12. Bioanalytical tools for the evaluation of organic micropollutants during sewage treatment, water recycling and drinking water generation.

    PubMed

    Macova, Miroslava; Toze, Simon; Hodgers, Leonie; Mueller, Jochen F; Bartkow, Michael; Escher, Beate I

    2011-08-01

    A bioanalytical test battery was used for monitoring organic micropollutants across an indirect potable reuse scheme testing sites across the complete water cycle from sewage to drinking water to assess the efficacy of different treatment barriers. The indirect potable reuse scheme consists of seven treatment barriers: (1) source control, (2) wastewater treatment plant, (3) microfiltration, (4) reverse osmosis, (5) advanced oxidation, (6) natural environment in a reservoir and (7) drinking water treatment plant. Bioanalytical results provide complementary information to chemical analysis on the sum of micropollutants acting together in mixtures. Six endpoints targeting the groups of chemicals with modes of toxic action of particular relevance for human and environmental health were included in the evaluation: genotoxicity, estrogenicity (endocrine disruption), neurotoxicity, phytotoxicity, dioxin-like activity and non-specific cell toxicity. The toxicity of water samples was expressed as toxic equivalent concentrations (TEQ), a measure that translates the effect of the mixtures of unknown and potentially unidentified chemicals in a water sample to the effect that a known reference compound would cause. For each bioassay a different representative reference compound was selected. In this study, the TEQ concept was applied for the first time to the umuC test indicative of genotoxicity using 4-nitroquinoline as the reference compound for direct genotoxicity and benzo[a]pyrene for genotoxicity after metabolic activation. The TEQ were observed to decrease across the seven treatment barriers in all six selected bioassays. Each bioassay showed a differentiated picture representative for a different group of chemicals and their mixture effect. The TEQ of the samples across the seven barriers were in the same order of magnitude as seen during previous individual studies in wastewater and advanced water treatment plants and reservoirs. For the first time a benchmarking was

  13. In vitro bioassay for reactive toxicity towards proteins implemented for water quality monitoring.

    PubMed

    Tang, Janet Y M; Glenn, Eva; Thoen, Hanne; Escher, Beate I

    2012-03-01

    Reactive organic chemicals comprise a large number of compounds with a variety of reactive moieties. While most assays for reactive toxicity focus on DNA damage, reactivity towards proteins can also lead to irreparable damage, but reactivity towards proteins is typically not included in any test battery for water quality assessment. Glutathione (GSH) is a small tripeptide whose cysteine moiety can serve as a model for nucleophilic sites on proteins. GSH is also an important indicator of detoxification processes and the redox status of cells and due to its protective role, depletion of GSH ultimately leads to adverse effects. A bioassay based on genetically modified Escherichia coli strains was used to quantify the specific reactivity towards the protein-like biological nucelophile GSH. The significance of GSH for detoxification was assessed by comparing the growth inhibition induced by reference chemicals or water samples in a GSH-deficient strain to its fully functional parent strain. The GSH deficient strain showed the same sensitivity as the GSH proficient strain to non-reactive and DNA damaging chemicals, but was more sensitive to chemicals that attack cysteine in proteins. The difference in effect concentrations for 50% inhibition of growth assessed as biomass increase (EC(50)) between the two strains indicates the relevance of GSH conjugation as a detoxification step as well as direct reactivity with cysteine-containing proteins. Seven reference compounds serving as positive and negative controls were investigated. The E. coli strain that lacks GSH was four times more sensitive towards the positive control Sea-Nine, while negative controls benzo[a]pyrene, 2-aminoanthracene, phenol, t-butylhydroquinone, methyl methane sulfonate and 4-nitroquinoline oxide showed equal effect concentrations in both strains. Water samples collected across an indirect potable reuse scheme representing the complete water cycle from sewage to drinking water in South East Queensland

  14. In vitro bioassay for reactive toxicity towards proteins implemented for water quality monitoring.

    PubMed

    Tang, Janet Y M; Glenn, Eva; Thoen, Hanne; Escher, Beate I

    2012-03-01

    Reactive organic chemicals comprise a large number of compounds with a variety of reactive moieties. While most assays for reactive toxicity focus on DNA damage, reactivity towards proteins can also lead to irreparable damage, but reactivity towards proteins is typically not included in any test battery for water quality assessment. Glutathione (GSH) is a small tripeptide whose cysteine moiety can serve as a model for nucleophilic sites on proteins. GSH is also an important indicator of detoxification processes and the redox status of cells and due to its protective role, depletion of GSH ultimately leads to adverse effects. A bioassay based on genetically modified Escherichia coli strains was used to quantify the specific reactivity towards the protein-like biological nucelophile GSH. The significance of GSH for detoxification was assessed by comparing the growth inhibition induced by reference chemicals or water samples in a GSH-deficient strain to its fully functional parent strain. The GSH deficient strain showed the same sensitivity as the GSH proficient strain to non-reactive and DNA damaging chemicals, but was more sensitive to chemicals that attack cysteine in proteins. The difference in effect concentrations for 50% inhibition of growth assessed as biomass increase (EC(50)) between the two strains indicates the relevance of GSH conjugation as a detoxification step as well as direct reactivity with cysteine-containing proteins. Seven reference compounds serving as positive and negative controls were investigated. The E. coli strain that lacks GSH was four times more sensitive towards the positive control Sea-Nine, while negative controls benzo[a]pyrene, 2-aminoanthracene, phenol, t-butylhydroquinone, methyl methane sulfonate and 4-nitroquinoline oxide showed equal effect concentrations in both strains. Water samples collected across an indirect potable reuse scheme representing the complete water cycle from sewage to drinking water in South East Queensland

  15. Evaluation of the cytotoxicity, mutagenicity and antimutagenicity of emerging edible plants.

    PubMed

    Yen, G C; Chen, H Y; Peng, H H

    2001-11-01

    This study evaluates the toxic, mutagenic and antimutagenic effects of emerging edible plants that are consumed as new leafy vegetables in Taiwan. Among eight plant extracts, only the extracts of Sol (Solanum nigrum L.) showed cytotoxicity to Salmonella typhimurium TA100 in the absence of S9 mix. The toxicity of extracts from different parts of the Sol plant, such as leaf and stem, immature fruit and mature fruit, towards S. typhimurium TA100 and human lymphocytes was also assayed. The immature fruit extracts of Sol exhibited strong cytotoxicity with dose dependence and induced significant DNA damage in human lymphocytes based on the comet assay. However, no mutagenicity was found in eight plant extracts to TA98 or TA100 either with or without the S9 mixture. Sol and Sec [Sechium edule (Jacq.) Swartz] extracts showed the strongest inhibitory effect towards the mutagenicity of 2-amino-3-methyl-imidazo[4,5-f]quinoline (IQ) in S. typhimurium TA98 and TA100; the ID(50) was less then 1 mg/plate. Cra [Crassocephalum creidioides (Benth.) S. Moore] extracts also expressed moderate antimutagenic activities towards IQ and benzo[a]pyrene (B[a]P) either in TA98 or in TA100; the ID(50) was 1.63-2.41 mg/plate. The extracts from Bas (Basella alba L.), Bou (Boussingaultia gracilis Miers var. pseudobaselloides Bailey), Cen (Centella asiatica L. Urban), Cor (Corchorus olitorius L.) and Por (Portulaca oleracea L.) showed weak to moderate inhibition of mutagenicity of IQ. However, the potential antimutagenicity of these plant extracts towards B[a]P was weaker than that towards IQ. For a direct mutagen, 4-nitroquinoline-N-oxide (NQNO), only the Sol extracts showed strong inhibitory effects in the TA100 system. The antimutagenic activity of water extracts of Sec was partly reduced by heating at 100 degrees C for 20 min. The heat-stable antimutagens in Sec extracts could be produced in the plant extract preparation process. Fractions with molecular weights above 30,000 showed the

  16. Comet assay in reconstructed 3D human epidermal skin models—investigation of intra- and inter-laboratory reproducibility with coded chemicals

    PubMed Central

    Pfuhler, Stefan

    2013-01-01

    Reconstructed 3D human epidermal skin models are being used increasingly for safety testing of chemicals. Based on EpiDerm™ tissues, an assay was developed in which the tissues were topically exposed to test chemicals for 3h followed by cell isolation and assessment of DNA damage using the comet assay. Inter-laboratory reproducibility of the 3D skin comet assay was initially demonstrated using two model genotoxic carcinogens, methyl methane sulfonate (MMS) and 4-nitroquinoline-n-oxide, and the results showed good concordance among three different laboratories and with in vivo data. In Phase 2 of the project, intra- and inter-laboratory reproducibility was investigated with five coded compounds with different genotoxicity liability tested at three different laboratories. For the genotoxic carcinogens MMS and N-ethyl-N-nitrosourea, all laboratories reported a dose-related and statistically significant increase (P < 0.05) in DNA damage in every experiment. For the genotoxic carcinogen, 2,4-diaminotoluene, the overall result from all laboratories showed a smaller, but significant genotoxic response (P < 0.05). For cyclohexanone (CHN) (non-genotoxic in vitro and in vivo, and non-carcinogenic), an increase compared to the solvent control acetone was observed only in one laboratory. However, the response was not dose related and CHN was judged negative overall, as was p-nitrophenol (p-NP) (genotoxic in vitro but not in vivo and non-carcinogenic), which was the only compound showing clear cytotoxic effects. For p-NP, significant DNA damage generally occurred only at doses that were substantially cytotoxic (>30% cell loss), and the overall response was comparable in all laboratories despite some differences in doses tested. The results of the collaborative study for the coded compounds were generally reproducible among the laboratories involved and intra-laboratory reproducibility was also good. These data indicate that the comet assay in EpiDerm™ skin models is a

  17. Evaluation of mutagenic and antimutagenic activities of alpha-bisabolol in the Salmonella/microsome assay.

    PubMed

    Gomes-Carneiro, M R; Dias, Daniela M M; De-Oliveira, A C A X; Paumgartten, Francisco J R

    2005-08-01

    alpha-Bisabolol (BISA) is a sesquiterpene alcohol found in the oils of chamomile (Matricaria chamomilla) and other plants. BISA has been widely used in dermatological and cosmetic formulations. This study was undertaken to investigate the mutagenicity and antimutagenicity of BISA in the Salmonella/microsome assay. Mutagenicity of BISA was evaluated with TA100, TA98, TA97a and TA1535 Salmonella typhimurium strains, without and with addition of S9 mixture. No increase in the number of his+ revertant colonies over the negative (solvent) control values was observed with any of the four tester strains. In the antimutagenicity assays, BISA was tested up to the highest nontoxic dose (i.e. 50 and 150 microg/plate, with and without S9 mix, respectively) against direct-acting (sodium azide, SA; 4-nitroquinoline-N-oxide, 4-NQNO; 2-nitrofluorene, 2-NF; and nitro-o-phenylenediamine, NPD) as well as indirect-acting (cyclophosphamide, CP; benzo[a]pyrene, B[a]P; aflatoxin B1, AFB1; 2-aminoanthracene, 2-AA; and 2-aminofluorene, 2-AF) mutagens. BISA did not alter mutagenic activity of SA and of NPD, and showed only a weak inhibitory effect on the mutagenicity induced by 4-NQNO and 2-NF. The mutagenic effects of AFB1, CP, B[a]P, 2-AA and 2-AF, on the other hand, were all markedly and dose-dependently reduced by BISA. It was also found that BISA inhibited pentoxyresorufin-o-depentylase (PROD, IC50 2.76 microM) and ethoxyresorufin-o-deethylase (EROD, 33.67 microM), which are markers for cytochromes CYP2B1 and 1A1 in rat liver microsomes. Since CYP2B1 converts AFB1 and CP into mutagenic metabolites, and CYP1A1 activates B[a]P, 2-AA and 2-AF, results suggest that BISA-induced antimutagenicity could be mediated by an inhibitory effect on the metabolic activation of these promutagens. PMID:15936245

  18. Study on the mutagenicity and antimutagenicity of beta-ionone in the Salmonella/microsome assay.

    PubMed

    Gomes-Carneiro, M R; Dias, Daniela M M; Paumgartten, Francisco J R

    2006-04-01

    beta-Ionone (BIO) is a degraded (C(13)) sesquiterpenoid compound found in a variety of edible and aromatic plants. BIO and other ionone derivatives have been used in fragrance products and as flavoring food additives. In this study we investigated the mutagenic and antimutagenic activities of BIO using the Salmonella/microsome assay. Mutagenicity was evaluated by two tests with Salmonella typhimurium strains TA100, TA98, TA97a and TA1535, without and with addition of S9 mixture. A first assay was performed by the plate incorporation procedure and a confirmation test by the pre-incubation method. In either test, no increase in the number of his(+) revertant colonies over the negative (solvent) control values was noted with any of the four tester strains thereby indicating that BIO was not genotoxic in the Salmonella assay. Antimutagenic activity was investigated by testing (by the plate incorporation method) different non-toxic doses of BIO against one or more non-toxic doses of direct-acting (sodium azide: SA, 4-nitroquinoline-N-oxide: 4-NQNO, 2-nitrofluorene: 2-NF and nitro-o-phenylenediamine: NPD) as well as indirect-acting (cyclophosphamide: CP, benzo[a]pyrene: B[a]P, aflatoxin B1: AFB1, 2-aminoanthracene: 2-AA, and 2-aminofluorene: 2-AF) mutagens. BIO did not alter the effects of any direct-acting mutagen or B[a]P and 2-AF. Mutagenic effects of AFB1 and CP, however, were markedly and dose-dependently antagonized by BIO. It has been reported that, in the rat liver, activation of B[a]P and 2-AF depend on CYP1A1 activity, and that CYP2B subfamily is involved in the metabolic activation of CP and AFB1. It has also been described that BIO is a potent inhibitor of CYP2B1/2 and a weaker inhibitor of CYP1A1. Therefore, antagonism of CP-and AFB1-induced mutagenic effects by BIO could have been mediated-at least in part-by the inhibition of CYP2B enzymes. PMID:16223554

  19. Binding effect of polychlorinated compounds and environmental carcinogens on rice bran fiber.

    PubMed

    Sera, Nobuyuki; Morita, Kunimasa; Nagasoe, Masami; Tokieda, Hisako; Kitaura, Taeko; Tokiwa, Hiroshi

    2005-01-01

    To accelerate the fecal excretion of polycyclic biphenyl (PCB), polychlorinated dibenzofurans (PCDFs), polychlorinated-p-dioxines (PCDDs) and various mutagens and carcinogens, their binding effect on rice bran fiber (RBF) was investigated for nine heterocyclic amines, six nitroarenes, 4-nitroquinoline-N-oxide, benzo[a]pyrene, furylfuramide, two kinds of flavonoid compounds and formaldehyde and ascorbic acid. PCBs, PCDFs and PCDDs suspended in nonane were incubated with RBF (10 mg/ml) at 37 degrees C and after centrifugation, unbound chemicals in the supernatant were analyzed by high-performance liquid chromatography (HPLC) and gas chromatography (GC). The binding effects on RBF were enhanced more than other dietary fibers (DFs), which were tested including corn, wheat bran, spinach, Hijiki (a kind of seaweed), sweet potatoes and burdock fibers. It was found that the binding effects were related to lignin contents. Binding of 3-amino-1(or 1,4)-dimethyl-5H-pyrido[4,3-b]indole (Trp-p-1 and Trp-p-2), food-derived carcinogens and 1-nitropyrene (1-NP), suspended in methanol, to RBF occurred within 10 min of incubation at 37 degrees C at pH 5-7, and decreased below pH 4; binding of food-derived carcinogens was pH dependent. The binding effects to RBF and pulp lignin were obtained at ratio of over 90%, while corn fiber and cellulose were at ratios of 4-30%. Polycyclic aromatic compounds were related to the number of rings, showing high binding effects to chemical structures with triple rings. Binding of 1-NP and PCB to RBF was not influenced in any aerobic and anaerobic bacterial cultures. It was also found that RBF was capable of binding even conjugates containing mutagens such as glucuronides and sulfates, as well as metabolites in urine. It was suggested, therefore, that mutagens and carcinogens were available for the fecal excretion of residual chemicals and their metabolites, and also for the fecal excretion of PCBs, PCDFs and related compound residues in patients of

  20. Expression of APC protein during tongue malignant transformation in galectin-3-deficient mice challenged by the carcinogen 4-nitroquniline-n-oxide

    PubMed Central

    de Souza, Marcus Vinicius Rodrigues; Servato, João Paulo Silva; Loyola, Adriano Mota; Cardoso, Sérgio Vitorino; Chammas, Roger; Liu, Fu-Tong; Silva, Marcelo José Barbosa; de Faria, Paulo Rogério

    2014-01-01

    Galectin-3 (Gal3) has been implicated in the development of different tumors because of its involvement in the Wnt signaling pathway by promoting beta-catenin translocation into the nucleus. The APC protein, a negative regulator of this pathway, has been strongly implicated in the development of colon cancer, but still has an undetermined role in the formation of oral cancer. Therefore, this study aimed to evaluate the relationship between Gal3, the Wnt signaling pathway, and APC expression in dysplasias and carcinomas developed experimentally in mice. Sixty galectin-3-deficient (Gal3-/-) and 60 wild-type (Gal3+/+) mice were early employed to be treated with the carcinogen 4NQO for 16 weeks and killed at either week 16 or week 32. Tongues were removed, processed and embedded in paraffin blocks. Sections 5 μm thick were made, and then stained by H&E to establish the diagnosis of dysplasia and carcinoma. Sections of 2 μm thickness were made to detect APC expression in these lesions by immunohistochemistry. Oral carcinogenesis occurred in both groups of mice, but no statistical difference was reached. APC expression was exclusively seen in the cytoplasm of all lesions studied. In the intragroup analysis, the majority of dysplasias and carcinomas exhibiting higher APC immunoreactivity was observed in Gal3-/- mice compared to Gal3+/+ mice, but no significant difference was found. However, a statistical difference was only observed between dysplastic lesions from two mice. Our results showed that neither the absence of Gal3 nor the APC protein appears to play a role in malignant transformation of the tongue. PMID:25031746

  1. The upr-1 gene encodes a catalytic subunit of the DNA polymerase zeta which is involved in damage-induced mutagenesis in Neurospora crassa.

    PubMed

    Sakai, W; Ishii, C; Inoue, H

    2002-05-01

    The upr-1 mutant was one of the first mutagen-sensitive mutants to be isolated in Neurospora crassa. However, the function of the upr-1 gene has not yet been elucidated, although some genetic and biochemical data have been accumulated. In order to clone the upr-1 gene, we performed a chromosome walk from the mat locus, the closest genetic marker to upr-1 for which a molecular probe was available, towards the centromere, and a chromosomal contig of about 300-400 kb was constructed. Some of these clones complemented the temperature sensitivity of the un-16 mutation, which is located between mat and upr-1. The un-16 gene was sequenced, and localized in the MIPS Neurospora crassa genome database. We then searched the regions flanking un-16 for homologs of known DNA repair genes, and found a gene homologous to the REV3 gene of budding yeast. The phenotype of the upr-1 mutant is similar to that of the yeast rev3 mutant. An ncrev3 mutant carrying mutations in the N. crassa REV3 homolog was constructed using the RIP (repeat-induced point mutation) process. The spectrum of mutagen sensitivity of the ncrev3 mutant was similar to that of the upr-1 mutant. Complementation tests between the upr-1 and ncrev3 mutations indicated that the upr-1 gene is in fact identical to the ncrev3 gene. To clarify the role of the upr-1 gene in DNA repair, the frequency of MMS and 4NQO-induced mutations was assayed using the ad-8 reversion test. The upr-1 mutant was about 10 times less sensitive to both chemicals than the wild type. The expression level of the upr-1 gene is increased on exposure to UV irradiation in the uvs-2 and mus-8 mutants, which belong to postreplication repair group, as well as in the wild type. All these results suggest that the product of the upr-1 gene functions in damage-induced mutagenesis and DNA translesion synthesis in N. crassa.

  2. Catechins are not major components responsible for anti-genotoxic effects of tea extracts against nitroarenes.

    PubMed

    Ohe, T; Marutani, K; Nakase, S

    2001-09-20

    The anti-genotoxic properties of tea leaf extracts were examined in a Salmonella umu-test. Seven non-fermented teas (green tea), one semi-fermented tea (oolong tea), two fermented teas (black tea and Chinese pu er tea) and two other teas were examined for their anti-genotoxic abilities and for their catechins contents. This was to study the relationship between catechins contents and anti-genotoxic activity of various tea leaf extracts. All types of tea extracts showed more potent suppressive effects against umu gene expression of the SOS response in Salmonella typhimurium TA1535/pSK 1002 induced by four nitroarenes (1-nitropyrene, 2-nitrofluorene, 3-nitrofluoranthene and a mixture of 1,6- and 1,8-dinitropyrene) rather than 4-NQO, AF-2 and MNNG. The anti-genotoxic effect of 12 tea leaf extracts on 1-NP, 2-NF, 3-NF and DNP decreased in the order: oolong tea (semi-fermented tea)>black tea (fermented tea)>sencha (non-fermented tea, an ordinary grade green tea)>tocyucya (other tea)>Chinese pu er tea (fermented tea). The amount of catechins (EGC, C, EGCG, EC and ECG) in various teas in decreasing order was non-fermented tea>semi-fermented tea>fermented tea>other tea. A remarkable feature was the effectiveness of black tea and Chinese pu er tea in suppressing the genotoxicity induced by nitroarenes, in spite of the fact that these fermented teas do not have high catechins contents. Statistical analysis showed that no significant (P<0.01) correlation was found between the anti-genotoxicity of tea extracts against nitroarenes and the catechins contents in tea leaf extracts. In further experiment, fractionation of sencha extract by HPLC revealed that anti-genotoxicity of the peak fraction corresponding to catechins accounted for <10% of the total anti-genotoxic activity of sencha extract against for 1-nitropyrene. These results suggest that catechins are not major components responsible for the anti-genotoxic effects of tea leaf extracts against direct-acting nitroarenes

  3. Single Event Effects (SEE) for Power Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs)

    NASA Technical Reports Server (NTRS)

    Lauenstein, Jean-Marie

    2011-01-01

    Single-event gate rupture (SEGR) continues to be a key failure mode in power MOSFETs. (1) SEGR is complex, making rate prediction difficult SEGR mechanism has two main components: (1) Oxide damage-- Reduces field required for rupture (2) Epilayer response -- Creates transient high field across the oxide.

  4. IN VIVO EVIDENCE OF FREE RADICAL FORMATION AFTER ASBESTOS INSTILLATION: AN ESR SPIN TRAPPING INVESTIGATION

    EPA Science Inventory


    It has been postulated that the in vivo toxicity of asbestos results from its catalysis of free radical generation. We examined in vivo radical production using electron spin resonance (ESR) coupled with the spin trap alpha-(4-pyridyl-1-oxide)-N-t-butylnitrone (4-POBN); 180 d...

  5. 49 CFR 173.2 - Hazardous materials classes and index to hazard class definitions.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    .... Division No. (if any) Name of class or division 49 CFR reference for definitions None Forbidden materials... material 173.124 5 5.1 Oxidizer 173.127 5 5.2 Organic peroxide 173.128 6 6.1 Poisonous materials 173.132...

  6. 77 FR 60334 - New Marking Standards for Parcels Containing Hazardous Materials

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-03

    ... Hazardous Materials Safety Administration (PHMSA) published final rule HM-215K (76 FR 3308- 3389), which... class 5.1 (oxidizing substances), hazard class 5.2 (organic peroxides) and hazard class 8 (corrosives...'' column (only) as follows:] 5 Oxidizing Substances, Only Mailable Limited Organic Peroxides....

  7. 49 CFR 173.2 - Hazardous materials classes and index to hazard class definitions.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    .... Division No. (if any) Name of class or division 49 CFR reference for definitions None Forbidden materials... material 173.124 5 5.1 Oxidizer 173.127 5 5.2 Organic peroxide 173.128 6 6.1 Poisonous materials 173.132...

  8. Mineralogy and geochemistry of Fe-Ti oxide and apatite (nelsonite) deposits and evaluation of the liquid immiscibility hypothesis.

    USGS Publications Warehouse

    Kolker, A.

    1982-01-01

    The modal mineralogy for 32 Fe-Ti oxides and apatites supports the 2:1 oxide:apatite ratio for these samples from New York, Quebec, Norway and Sweden. Accessory minerals include: biotite, clinoamphibole, spinel, zircon and sulphides, oxygen fugacities range from 10-11 to 10-20, and T 600o to 1000oC. - K.A.R.

  9. RAPID MEASUREMENT OF AQUEOUS HYDROXYL RADICAL CONCENTRATIONS IN STEADY-STATE HO· FLUX SYSTEMS

    EPA Science Inventory

    The spin-trap compound a-(4-pyridyl-1-oxide)-N-tert-butyl-nitrone (4-POBN) is utilized for the detection and quantitation of the hydroxyl radical (HO·) in aqueous solution. Capillary electrophoresis enables rapid analysis of the probe compound. The thermally unstable HO· radical ...

  10. 49 CFR 173.2a - Classification of a material having more than one hazard.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...) Division 6.1 (poisonous liquids), Packing Group I, poisonous-by-inhalation only. (6) A material that meets... (Division 4.1). (8) Class 3 (flammable liquids), Class 8 (corrosive materials), Division 4.1 (flammable...), Division 5.1 (oxidizers) or Division 6.1 (poisonous liquids or solids other than Packing Group I,...

  11. 49 CFR 173.2a - Classification of a material having more than one hazard.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...) Division 6.1 (poisonous liquids), Packing Group I, poisonous-by-inhalation only. (6) A material that meets... (Division 4.1). (8) Class 3 (flammable liquids), Class 8 (corrosive materials), Division 4.1 (flammable...), Division 5.1 (oxidizers) or Division 6.1 (poisonous liquids or solids other than Packing Group I,...

  12. 49 CFR 173.2a - Classification of a material having more than one hazard.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...) Division 6.1 (poisonous liquids), Packing Group I, poisonous-by-inhalation only. (6) A material that meets... (Division 4.1). (8) Class 3 (flammable liquids), Class 8 (corrosive materials), Division 4.1 (flammable...), Division 5.1 (oxidizers) or Division 6.1 (poisonous liquids or solids other than Packing Group I,...

  13. 49 CFR 173.2a - Classification of a material having more than one hazard.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...) Division 6.1 (poisonous liquids), Packing Group I, poisonous-by-inhalation only. (6) A material that meets... (Division 4.1). (8) Class 3 (flammable liquids), Class 8 (corrosive materials), Division 4.1 (flammable...), Division 5.1 (oxidizers) or Division 6.1 (poisonous liquids or solids other than Packing Group I,...

  14. 49 CFR 172.400 - General labeling requirements.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... § 172.400a, each person who offers for transportation or transports a hazardous material in any of the... packaging, other than a cargo tank, portable tank, or tank car, with a volumetric capacity of less than 18... SOLID 172.420 4.2 SPONTANEOUSLY COMBUSTIBLE 172.422 4.3 DANGEROUS WHEN WET 172.423 5.1 OXIDIZER...

  15. 49 CFR 172.400 - General labeling requirements.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... § 172.400a, each person who offers for transportation or transports a hazardous material in any of the... packaging, other than a cargo tank, portable tank, or tank car, with a volumetric capacity of less than 18... SOLID 172.420 4.2 SPONTANEOUSLY COMBUSTIBLE 172.422 4.3 DANGEROUS WHEN WET 172.423 5.1 OXIDIZER...

  16. 49 CFR 172.400 - General labeling requirements.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... § 172.400a, each person who offers for transportation or transports a hazardous material in any of the... packaging, other than a cargo tank, portable tank, or tank car, with a volumetric capacity of less than 18... SOLID 172.420 4.2 SPONTANEOUSLY COMBUSTIBLE 172.422 4.3 DANGEROUS WHEN WET 172.423 5.1 OXIDIZER...

  17. 49 CFR 172.400 - General labeling requirements.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... § 172.400a, each person who offers for transportation or transports a hazardous material in any of the... packaging, other than a cargo tank, portable tank, or tank car, with a volumetric capacity of less than 18... SOLID 172.420 4.2 SPONTANEOUSLY COMBUSTIBLE 172.422 4.3 DANGEROUS WHEN WET 172.423 5.1 OXIDIZER...

  18. Surface-enhanced raman scattering from ethylenediaminetetraacetic-disodium salt and nitrate ions on silver electrodes

    NASA Astrophysics Data System (ADS)

    Wetzel, H.; Pettinger, B.; Wenning, U.

    1980-10-01

    Surface-enhanced Raman scattering (SERS) from ethylenediaminetetraacetic-disodium salt adsorbed on silver electrodes has been obtained for the 913, 935 and 1408 cm -1 modes. Addition of this salt to NaNO 3 solutions leads to an enhancement of the NO -3 band at 1050 cm -1. Oxidation/reduction cycles leading to surface roughening and a photochemical reaction caused by the exciting light are prerequisites for these enhancements. The SER signal can irreversibly be quenched by cathodic polarisation.

  19. 33 CFR 160.204 - Definitions.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... listed as a Division 5.1 (oxidizing) material in 49 CFR 172.101 except when carried as CDC residue; and... following: (1) Division 1.1 or 1.2 explosives as defined in 49 CFR 173.50. (2) Division 1.5D blasting agents for which a permit is required under 49 CFR 176.415 or, for which a permit is required as a...

  20. 33 CFR 160.204 - Definitions.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... (ii) Ammonium nitrate based fertilizer listed as a Division 5.1 (oxidizing) material in 49 CFR 172.101... following: (1) Division 1.1 or 1.2 explosives as defined in 49 CFR 173.50. (2) Division 1.5D blasting agents for which a permit is required under 49 CFR 176.415 or, for which a permit is required as a...

  1. 33 CFR 160.204 - Definitions.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... (ii) Ammonium nitrate based fertilizer listed as a Division 5.1 (oxidizing) material in 49 CFR 172.101... following: (1) Division 1.1 or 1.2 explosives as defined in 49 CFR 173.50. (2) Division 1.5D blasting agents for which a permit is required under 49 CFR 176.415 or, for which a permit is required as a...

  2. 33 CFR 160.204 - Definitions.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... (ii) Ammonium nitrate based fertilizer listed as a Division 5.1 (oxidizing) material in 49 CFR 172.101... following: (1) Division 1.1 or 1.2 explosives as defined in 49 CFR 173.50. (2) Division 1.5D blasting agents for which a permit is required under 49 CFR 176.415 or, for which a permit is required as a...

  3. Ybp1 and Gpx3 Signaling in Candida albicans Govern Hydrogen Peroxide-Induced Oxidation of the Cap1 Transcription Factor and Macrophage Escape

    PubMed Central

    Patterson, Miranda J.; McKenzie, Christopher G.; Smith, Deborah A.; da Silva Dantas, Alessandra; Sherston, Sam; Veal, Elizabeth A.; Morgan, Brian A.; MacCallum, Donna M.

    2013-01-01

    Abstract Aims: As Candida albicans is the major fungal pathogen of humans, there is an urgent need to understand how this pathogen evades toxic reactive oxygen species (ROS) generated by the host immune system. A key regulator of antioxidant gene expression, and thus ROS resistance, in C. albicans is the AP-1-like transcription factor Cap1. Despite this, little is known regarding the intracellular signaling mechanisms that underlie the oxidation and activation of Cap1. Therefore, the aims of this study were; (i) to identify the regulatory proteins that govern Cap1 oxidation, and (ii) to investigate the importance of Cap1 oxidation in C. albicans pathogenesis. Results: In response to hydrogen peroxide (H2O2), but not glutathione-depleting/modifying oxidants, Cap1 oxidation, nuclear accumulation, phosphorylation, and Cap1-dependent gene expression, is mediated by a glutathione peroxidase-like enzyme, which we name Gpx3, and an orthologue of the Saccharomyces cerevisiae Yap1 binding protein, Ybp1. In addition, Ybp1 also functions to stabilise Cap1 and this novel function is conserved in S. cerevisiae. C. albicans cells lacking Cap1, Ybp1, or Gpx3, are unable to filament and thus, escape from murine macrophages after phagocytosis, and also display defective virulence in the Galleria mellonella infection model. Innovation: Ybp1 is required to promote the stability of fungal AP-1-like transcription factors, and Ybp1 and Gpx3 mediated Cap1-dependent oxidative stress responses are essential for the effective killing of macrophages by C. albicans. Conclusion: Activation of Cap1, specifically by H2O2, is a prerequisite for the subsequent filamentation and escape of this fungal pathogen from the macrophage. Antioxid. Redox Signal. 19, 2244–2260. PMID:23706023

  4. Preliminary Investigation of the Effect of Surface Treatment on the Strength of a Titanium Carbide - 30 Percent Nickel Base Cermet

    NASA Technical Reports Server (NTRS)

    Robins, Leonard; Grala, Edward M

    1957-01-01

    Specimens of a nickel-bonded titanium carbide cermet were given the following surface treatments: (1) grinding, (2) lapping, (3) blast cleaning, (4) acid roughening, (5) oxidizing, and (6) oxidizing and refinishing. Room-temperature modulus-of-rupture and impact strength varied with the different surface treatments. Considerable strength losses resulted from the following treatments: (1) oxidation at 1600 F for 100 hours, (2) acid roughening, and (3) severe grinding with 60-grit silicon carbide abrasive. The strength loss after oxidation was partially recovered by grit blasting or diamond grinding.

  5. Elemental sulfur disproportionation in the redox condensation reaction between o-halonitrobenzenes and benzylamines.

    PubMed

    Nguyen, Thanh Binh; Ermolenko, Ludmila; Retailleau, Pascal; Al-Mourabit, Ali

    2014-12-01

    The disproportionation of elemental sulfur at moderate temperatures is investigated in the redox condensation involving o-halonitrobenzenes 1 and benzylamines 2. As a redox moderator, elemental sulfur plays the dual role of both electron donor and acceptor, generating its lowest and highest oxidation states: S(-2) (sulfide equivalent) in benzothiazole 3 and S(+6) (sulfate equivalent) in sulfamate 4, and filling the electron gap of the global redox condensation process. Along with this process, a cascade of reactions of reduction of the nitro group of 1, oxidation of the aminomethyl group of 2, metal-free aromatic halogen substitution, and condensation finally led to 2-arylbenzothiazoles 3.

  6. Initiation of in vitro lipid peroxidation by N-hydroxynorcocaine and norcocaine nitroxide.

    PubMed

    Rosen, G M; Kloss, M W; Rauckman, E J

    1982-11-01

    Norcocaine nitroxide and N-hydroxynorcocaine were found to stimulate hepatic microsomal lipid peroxidation in vitro, as measured by spin-trapping techniques using the spin trap alpha-[4-pyridyl-1-oxide]-N-tert-butylnitrone. It was determined that either norcocaine nitroxide or N-hydroxynorcocaine markedly enhanced the rate of spin trapping of lipid peroxyl radicals when added to hepatic microsomal preparations. Glutathione, in the presence of dialyzed cytosol, inhibited the formation of lipid peroxyl spin-trapped adducts. This finding suggests that cytosolic glutathione-dependent enzymes perhaps including glutathione peroxidase play an important role in the prevention of norcocaine nitroxide-or N-hydroxynorcocaine-mediated lipid peroxidation.

  7. Surface interaction mechanisms of 5eV atomic oxygen: Data analysis from the UAH experiment on STS-8

    NASA Technical Reports Server (NTRS)

    Gregory, J. C.

    1987-01-01

    The University of Alabama in Huntsville (UAH) experiment which flew on the STS-8 mission had several objectives which were mostly of a speculative nature since so little was known of the processes of interest. The experiment provided original, if limited, data on: (1) oxidation of metal surfaces, (2) reaction rates of atomic oxygen with carbon and other surfaces and the dependence of these rates on temperature, and (3) the angular distribution of 5eV atoms scattered off a solid surface. Provided is a review of the results, with reference given to fuller published accounts where these are available.

  8. High-performance capillary electrophoresis determination of pyrithione in antidandruff preparations and shampoos.

    PubMed

    Peña-Méndez, E M; Havel, J; Malecek, J

    1997-01-01

    A simple and rapid high-performance capillary electrophoresis (HPCE) method for the determination of 2-mercaptopyridine-1-oxide (pyrithione) was developed. After addition of ethylenediaminetetraacetic acid (EDTA), pyrithione was determined in the form of the free anion using 50 mM borate (pH 9.2) as background electrolyte and was detected at 244 nm with a limit of detection (LOD) of 0.636 ppm (S/N = 3). The method was used to check the purity of pyrithione preparations and for the determination of pyrithione in shampoo.

  9. Beryllium chemistry the safe way: a theoretical evaluation of low oxidation state beryllium compounds.

    PubMed

    Couchman, Shannon A; Holzmann, Nicole; Frenking, Gernot; Wilson, David J D; Dutton, Jason L

    2013-08-28

    A theoretical study of compounds containing Be in the +1 or 0 oxidation state has been carried out. The molecules considered containing Be in the +1 oxidation state are analogues of the important Mg(I)-Mg(I) dimer supported by the β-diketiminate ligand. The molecules in the 0 oxidation state are NHC supported compounds analogous to "molecular allotropes" which has recently become a topic of importance in p-block chemistry. In this case, our results demonstrate that the Be(0) complexes are far more stable than the analogous Mg(0) complexes, highlighting the opportunities afforded in Be chemistry, despite the challenges presented by the toxicity of Be compounds.

  10. Mechanistic studies of carbon monoxide reduction

    SciTech Connect

    Geoffroy, G.L.

    1990-06-12

    The progress made during the current grant period (1 January 1988--1 April 1990) in three different areas of research is summarized. The research areas are: (1) oxidatively-induced double carbonylation reactions to form {alpha}-ketoacyl complexes and studies of the reactivity of the resulting compounds, (2) mechanistic studies of the carbonylation of nitroaromatics to form isocyanates, carbamates, and ureas, and (3) studies of the formation and reactivity of unusual metallacycles and alkylidene ligands supported on binuclear iron carbonyl fragments. 18 refs., 5 figs., 1 tab.

  11. (2R,3S,4R)-3,4-Isopropyl­idenedi­oxy-2-(phenyl­sulfonyl­meth­yl)pyrrolidin-1-ol

    PubMed Central

    Flores, Mari Fe; Garcia, Pilar; M. Garrido, Narciso; Sanz, Francisca; Diez, David

    2012-01-01

    The title compound, C14H19NO5S, was prepared by nucleophilic addition of the lithium derivative of methyl­phenyl­sulfone to (3S,4R)-3,4-isopropyl­idene­dioxy­pyrroline 1-oxide. There are four mol­ecules in the asymmetric unit. The crystal structure determination confirms the configuration of the chiral centres as 2R,3S,4R. In the crystal, pairs of O—H⋯N hydrogen bonds link the mol­ecules into dimers. PMID:22904989

  12. Reexamination of the microsomal transformation of N-hydroxynorcocaine to norcocaine nitroxide.

    PubMed

    Lloyd, R V; Shuster, L; Mason, R P

    1993-04-01

    Cocaine is known to be associated with hepatotoxicity in laboratory animals, and there is recent evidence that it also induces liver damage in humans. In both cases an N-oxidative pathway is responsible. Cocaine (NCN) is first N-demethylated to norcocaine, followed by oxidation to N-hydroxynorcocaine (NCNOH) and norcocaine nitroxide (NCNO.). On the basis of ESR studies of NCNOH with rat liver microsomes, it has been proposed that NCNO. induces hepatotoxicity by futile redox cycling between NCNO. and NCNOH at the expense of NADPH. The reaction is reported to be accompanied by formation of superoxide and lipid peroxyl radicals. It has also been reported that the same toxic sequence occurs with rat brain microsomes, leading to the formation of reactive free radicals in the brain. We have reexamined the microsomal metabolism of NCNOH to investigate the mechanism more thoroughly. Spin traps [5,5-dimethyl-1-pyrroline N-oxide and alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone] were used to investigate the formation of reactive free radicals, including superoxide, in liver and brain microsomal incubations. In agreement with the literature, we detected a six-line spectrum of a radical adduct of alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone from liver microsome incubations. In contrast, our results showed that brain microsomes were completely inactive, contrary to the literature. In addition, we did not find any NCNO.- or NCNOH-dependent formation of superoxide with either brain or liver microsomes.

  13. Profiling Metal Oxides with Lipids: Magnetic Liposomal Nanoparticles Displaying DNA and Proteins.

    PubMed

    Wang, Feng; Zhang, Xiaohan; Liu, Yibo; Lin, Zhi Yuan William; Liu, Biwu; Liu, Juewen

    2016-09-19

    Metal oxides include many important materials with various surface properties. For biomedical and analytical applications, it is desirable to engineer their biocompatible interfaces. Herein, a phosphocholine liposome (DOPC) and its headgroup dipole flipped counterpart (DOCP) were mixed with ten common oxides. Using the calcein leakage assay, cryo-TEM, and ζ-potential measurement, these oxides were grouped into three types. The type 1 oxides (Fe3 O4 , TiO2 , ZrO2 , Y2 O3 , ITO, In2 O3 , and Mn2 O3 ) form supported bilayers only with DOCP. Type 2 (SiO2 ) forms supported bilayers only with DOPC; type 3 (ZnO and NiO) are cationic and damage lipid membranes. Magnetic Fe3 O4 nanoparticles were further studied for conjugation of fluorophores, proteins, and DNA to the supported DOCP bilayers via lipid headgroup labeling, covalent linking, or lipid insertion. Delivery of the conjugates to cells and selective DNA hybridization were demonstrated. This work provides a general solution for coating the type 1 oxides with a simple mixing in water, facilitating applications in biosensing, separation, and nanomedicine. PMID:27539511

  14. A chloroplast light-regulated oxidative sensor for moderate light intensity in Arabidopsis.

    PubMed

    Dangoor, Inbal; Peled-Zehavi, Hadas; Wittenberg, Gal; Danon, Avihai

    2012-05-01

    The transition from dark to light involves marked changes in the redox reactions of photosynthetic electron transport and in chloroplast stromal enzyme activity even under mild light and growth conditions. Thus, it is not surprising that redox regulation is used to dynamically adjust and coordinate the stromal and thylakoid compartments. While oxidation of regulatory proteins is necessary for the regulation, the identity and the mechanism of action of the oxidizing pathway are still unresolved. Here, we studied the oxidation of a thylakoid-associated atypical thioredoxin-type protein, ACHT1, in the Arabidopsis thaliana chloroplast. We found that after a brief period of net reduction in plants illuminated with moderate light intensity, a significant oxidation reaction of ACHT1 arises and counterbalances its reduction. Interestingly, ACHT1 oxidation is driven by 2-Cys peroxiredoxin (Prx), which in turn eliminates peroxides. The ACHT1 and 2-Cys Prx reaction characteristics in plants further indicated that ACHT1 oxidation is linked with changes in the photosynthetic production of peroxides. Our findings that plants with altered redox poise of the ACHT1 and 2-Cys Prx pathway show higher nonphotochemical quenching and lower photosynthetic electron transport infer a feedback regulatory role for this pathway.

  15. A Chloroplast Light-Regulated Oxidative Sensor for Moderate Light Intensity in Arabidopsis[C][W

    PubMed Central

    Dangoor, Inbal; Peled-Zehavi, Hadas; Wittenberg, Gal; Danon, Avihai

    2012-01-01

    The transition from dark to light involves marked changes in the redox reactions of photosynthetic electron transport and in chloroplast stromal enzyme activity even under mild light and growth conditions. Thus, it is not surprising that redox regulation is used to dynamically adjust and coordinate the stromal and thylakoid compartments. While oxidation of regulatory proteins is necessary for the regulation, the identity and the mechanism of action of the oxidizing pathway are still unresolved. Here, we studied the oxidation of a thylakoid-associated atypical thioredoxin-type protein, ACHT1, in the Arabidopsis thaliana chloroplast. We found that after a brief period of net reduction in plants illuminated with moderate light intensity, a significant oxidation reaction of ACHT1 arises and counterbalances its reduction. Interestingly, ACHT1 oxidation is driven by 2-Cys peroxiredoxin (Prx), which in turn eliminates peroxides. The ACHT1 and 2-Cys Prx reaction characteristics in plants further indicated that ACHT1 oxidation is linked with changes in the photosynthetic production of peroxides. Our findings that plants with altered redox poise of the ACHT1 and 2-Cys Prx pathway show higher nonphotochemical quenching and lower photosynthetic electron transport infer a feedback regulatory role for this pathway. PMID:22570442

  16. Profiling Metal Oxides with Lipids: Magnetic Liposomal Nanoparticles Displaying DNA and Proteins.

    PubMed

    Wang, Feng; Zhang, Xiaohan; Liu, Yibo; Lin, Zhi Yuan William; Liu, Biwu; Liu, Juewen

    2016-09-19

    Metal oxides include many important materials with various surface properties. For biomedical and analytical applications, it is desirable to engineer their biocompatible interfaces. Herein, a phosphocholine liposome (DOPC) and its headgroup dipole flipped counterpart (DOCP) were mixed with ten common oxides. Using the calcein leakage assay, cryo-TEM, and ζ-potential measurement, these oxides were grouped into three types. The type 1 oxides (Fe3 O4 , TiO2 , ZrO2 , Y2 O3 , ITO, In2 O3 , and Mn2 O3 ) form supported bilayers only with DOCP. Type 2 (SiO2 ) forms supported bilayers only with DOPC; type 3 (ZnO and NiO) are cationic and damage lipid membranes. Magnetic Fe3 O4 nanoparticles were further studied for conjugation of fluorophores, proteins, and DNA to the supported DOCP bilayers via lipid headgroup labeling, covalent linking, or lipid insertion. Delivery of the conjugates to cells and selective DNA hybridization were demonstrated. This work provides a general solution for coating the type 1 oxides with a simple mixing in water, facilitating applications in biosensing, separation, and nanomedicine.

  17. Synthesis and Coordination Properties of Trifluoromethyl Decorated Derivatives of 2,6-Bis[(diphenylphosphinoyl)methyl]pyridine N-Oxide Ligands with Lanthanide Ions

    SciTech Connect

    Pailloux, Sylvie; Shirima, Cornel Edicome; Ray, Alicia D.; Duesler, Eileen N.; Paine, Robert T.; Klaehn, John D.; McIlwain, Michael E; Hay, Benjamin

    2009-01-01

    Phosphinoyl Grignard-based substitutions on 2,6-bis(chloromethyl)pyridine followed by N-oxidation of the intermediate 2,6-bis(phosphinoyl)methyl pyridine compounds with mCPBA give the target trifunctional ligands 2,6-bis[bis-(2-trifluoromethyl-phenyl)-phosphinoylmethyl]-pyridine 1-oxide (2a) and 2,6-bis[bis-(3,5-bis-trifluoromethyl-phenyl)-phosphinoylmethyl]-pyridine 1-oxide (2b) in high yields. The ligands have been spectroscopically characterized, the molecular structures confirmed by single crystal X-ray diffraction methods and the coordination chemistry surveyed with lanthanide nitrates. Single crystal X-ray diffraction analyses are described for the coordination complexes Nd(2a)(NO3)3, Nd(2a)(NO3)3 (CH3CN)0.5, Eu(2a)(NO3)3 and Nd(2b)(NO3)3 (H2O)1.25; in each case the ligand binds in a tridentate mode to the Ln(III) cation. These structures are compared with the structures found for lanthanide coordination complexes of the parent NOPOPO ligand, [Ph2P(O)CH2]2C5H3NO.

  18. Insulin-stimulated intracellular hydrogen peroxide production in rat epididymal fat cells.

    PubMed

    May, J M; de Haën, C

    1979-04-10

    Insulin stimulation of hydrogen peroxide production by rat epididymal fat cells was investigated by studying the oxidation of formate to CO2 by endogenous catalase. Under optimal concentrations of formate (0.1 to 1 mM) and glucose (0.275 mM), insulin stimulated formate oxidation 1.5- to 2.0-fold. Inhibitors of catalase activity, including nitrite and azide, inhibited both basal and insulin-stimulated formate oxidation at concentrations that did not interfere with insulin effects on glucose C-1 oxidation or glucose H-3 incorporation into lipids. The addition of exogenous catalase increased formate oxidation only slightly, while exogenous H2O2 (0.5 mM) stimulated formate oxidation by endogenous catalase strongly. These data indicate that the insulin-stimulated H2O2 production was intracellular. Insulin dose-response curves for formate oxidation were identical with those for glucose H-3 incorporation into lipids. The dependence of relative insulin effects on the logarithm of the glucose concentration was bell-shaped for formate oxidation and correlated highly with the coresponding dependences of glucose C-1 oxidation and glucose H-3 incorporation into lipids. This suggests that insulin stimulation of intracellular H2O2 production is linked to glucose metabolism. Since it is known that extracellular H2O2 can mimic insulin in several respects, these observations suggest that H2O2 may act as a "second messenger" for the observed effects of insulin.

  19. Compatibility Study of DNTF with Some Insensitive Energetic Materials and Inert Materials

    NASA Astrophysics Data System (ADS)

    Li, Xi; Wang, Bo-Liang; Lin, Qiu-Han; Chen, Li-Ping

    2016-10-01

    The compatibility of 3,4-dinitrofurazanfuroxan (DNTF) with insensitive energetic materials and inert materials was studied in detail using differential scanning calorimetry (DSC). 2,4,6-Trinitrotoluene (TNT), 2,4,6-triamino-1,3,5-trinitrobenzene (TATB), 3-nitro-1,2,4-triazol-5-one (NTO), 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105), 2,6-diamino-3,5-dinitropyridine-1-oxide (ANPyO), and 5-amino-1H-tetrazole nitrate (5-ATEZN) are used as insensitive energetic materials, and polymer(vinyl acetate) (PVAC), hydroxyl-terminated polybutadiene (HTPB), dinoctylsebacate (DOS), 2,4-dinitrotoluene (DNT), and wax are used as inert materials. The results show that DNTF/TNT and DNTF/5-ATEZN possess good compatibility, DNTF/NTO and DNTF/TATB have moderate compatibility, and the compatibility of DNTF/LLM-105 and DNTF/PVAC is poor; in addition, DNTF/ANPyO, DNTF/HTPB, DNTF/DNT, DNTF/DOS, and DNTF/wax have bad compatibility.

  20. Synthesis and f-element ligation properties of NCMPO-decorated pyridine N-oxide platforms

    SciTech Connect

    Ouizem, Sabrina; Rosario-Amorin, Daniel; Dickie, D. A.; Paine, Robert T.; De Bettencourt-Dias, Ana; Hay, Benjamin; Podair, Julien; Delmau, Laetitia Helene

    2014-01-01

    Stepwise syntheses of 2-{[2-(diphenylphosphoryl)acetamido]methyl}pyridine 1-oxide, 2-[Ph2P(O)CH2C(O)N(H)CH2]C5H4NO (6), 2-{[2-(diphenylphosphoryl)acetamido]methyl}-6-[(diphenylphosphoryl)methyl]pyridine 1-oxide, 2-[Ph2P(O)CH2C(O)N(H)CH2]-6-[Ph2P(O)CH2]C5H3NO (7) and 2,6-bis{[2-(diphenylphosphoryl)acetamido]methyl}pyridine 1-oxide, 2,6-[Ph2P(O)CH2C(O)N(H)CH2]2C5H3NO (8), are reported along with spectroscopic characterization data and single crystal X-ray diffraction structure determination for 6 2H2O, 7 and 2,6-[Ph2P(O)CH2C(O)N(H)CH2]2C5H3N MeOH 18 MeOH, the pyridine precursor of 8. Molecular mechanics computations indicate that 6, 7 and 8 should experience minimal steric hindrance to donor group reorganization that would permit tridentate, tetradentate and pentadentate docking structures for the respective ligands on lanthanide cations. However, crystal structure determination for the lanthanide complexes, {[Yb(6)(NO3)3] (MeOH)}n, {[Lu(6)(NO3)3] (MeOH)}n, [Er(6)2(H2O)2](NO3)3 (H2O)4}n, {[La(13)(NO3)3(MeOH)] (MeOH)}n, {[Eu(7)(NO3)2(EtOAc)0.5(H2O)0.5](NO3)}2 MeOH and [Dy3(7)4(NO3)4(H2O)2](NO3)5 (MeOH)5 (H2O)2 reveal solid-state structures with mixed chelating/bridging ligand:Ln(III) interactions that employ lower than the maximal denticity. The binding of 6 and 7 with Eu(III) in the solid state and in MeOH solutions is also accessed by emission spectroscopy. The acid dependence for solvent extractions with 6 and 7 in 1,2-dichloroethane for Eu(III) and Am(III) in nitric acid solutions is described and compared with the behavior of n-octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide (OPhDiBCMPO, 1b) and 2-[(diphenyl)phosphinoylmethyl]pyridine N-oxide (DPhNOPO, 4a).

  1. Recovery of cobalt and copper from complex sulfide concentrates

    SciTech Connect

    Dannenberg, R.O.; Gardner, P.C.; Crane, S.R.; Seidel, D.C.

    1987-01-01

    The Bureau conducted bench-scale research on a process for treating cobaltite concentrates, comprising (1) oxidative pressure leaching, (2) jarosite precipitation followed by H/sub 2/O/sub 2/ oxidation and pH control to remove iron and arsenic, (3) copper solvent extraction with a mixed hydroxyoxime-amine extractant, (4) copper electrowinning from recirculating acidic strip liquor, (5) selective cobalt extraction from copper solvent extraction raffinate with a phosphinic and extractant, and (6) electrowinning of cobalt from a recirculating weak acid strip liquor. Overall cobalt and copper recoveries were 91.7 and 84.1 pct, respectively. Electrowon products assayed 99.8 pct Co and 99.89 ct Cu.

  2. Oxidation of methyl groups by grass grubs and vertebrate liver enzymes

    PubMed Central

    Hook, G. E. R.; Smith, J. N.

    1967-01-01

    1. Oxidation rates of p-nitrotoluene, p-acetamidotoluene and p-toluidine by intact grass grubs and vertebrate liver preparations were measured. 2. The effect of p-substitution in increasing the rate of conversion of the methyl into a carboxy group was in the order acetamido> nitro[unk] amino in mice and grass grubs. 3. Rates of oxidation of the N-methyl group in some alkylaryl N-methylcarbamates was measured and the effect of ring substituents in increasing the rate was in the order hydrogen> o-methyl or o-isopropyl> p-methyl or p-isopropyl> m-methyl or m-isopropyl. 4. Rates of oxidation of the N-methyl groups were similar to those of the p-substituted toluenes. PMID:6029608

  3. OZONE TREATMENT OF SOLUBLE ORGANICS IN PRODUCED WATER

    SciTech Connect

    Klasson, KT

    2002-03-14

    This project was an extension of previous research to improve the applicability of ozonation and will help address the petroleum-industry problem of treating produced water containing soluble organics. The goal of this project was to maximize oxidation of hexane-extractable organics during a single-pass operation. The project investigated: (1) oxidant production by electrochemical and sonochemical methods, (2) increasing the mass transfer rate in the reactor by forming microbubbles during ozone injection into the produced water, and (3) using ultraviolet irradiation to enhance the reaction if needed. Several types of methodologies for treatment of soluble organics in synthetic and actual produced waters have been performed. The technologies tested may be categorized as follows: (1) Destruction via sonochemical oxidation at different pH, salt concentration, ultraviolet irradiation, and ferrous iron concentrations. (2) Destruction via ozonation at different pH, salt concentration, hydrogen peroxide concentrations, ultraviolet irradiation, temperature, and reactor configurations.

  4. Metabolomics reveals impaired maturation of HDL particles in adolescents with hyperinsulinaemic androgen excess

    PubMed Central

    Samino, Sara; Vinaixa, Maria; Díaz, Marta; Beltran, Antoni; Rodríguez, Miguel A.; Mallol, Roger; Heras, Mercedes; Cabre, Anna; Garcia, Lorena; Canela, Nuria; de Zegher, Francis; Correig, Xavier; Ibáñez, Lourdes; Yanes, Oscar

    2015-01-01

    Hyperinsulinaemic androgen excess (HIAE) in prepubertal and pubertal girls usually precedes a broader pathological phenotype in adulthood that is associated with anovulatory infertility, metabolic syndrome and type 2 diabetes. The metabolic derangements that determine these long-term health risks remain to be clarified. Here we use NMR and MS-based metabolomics to show that serum levels of methionine sulfoxide in HIAE girls are an indicator of the degree of oxidation of methionine-148 residue in apolipoprotein-A1. Oxidation of apo-A1 in methionine-148, in turn, leads to an impaired maturation of high-density lipoproteins (HDL) that is reflected in a decline of large HDL particles. Notably, such metabolic alterations occur in the absence of impaired glucose tolerance, hyperglycemia and hypertriglyceridemia, and were partially restored after 18 months of treatment with a low-dose combination of pioglitazone, metformin and flutamide. PMID:26099471

  5. Oxidation, carburization and/or sulfidation resistant iron aluminide alloy

    DOEpatents

    Sikka, Vinod K.; Deevi, Seetharama C.; Fleischhauer, Grier S.; Hajaligol, Mohammad R.; Lilly, Jr., A. Clifton

    2003-08-19

    The invention relates generally to aluminum containing iron-base alloys useful as electrical resistance heating elements. The aluminum containing iron-base alloys have improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The alloy has an entirely ferritic microstructure which is free of austenite and includes, in weight %, over 4% Al, .ltoreq.1% Cr and either .gtoreq.0.05% Zr or Zro.sub.2 stringers extending perpendicular to an exposed surface of the heating element or .gtoreq.0.1% oxide dispersoid particles. The alloy can contain 14-32% Al, .ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Zr, .ltoreq.1% C, .ltoreq.0.1% B. .ltoreq.30% oxide dispersoid and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1% rare earth metal, .ltoreq.1% oxygen, .ltoreq.3% Cu, balance Fe.

  6. Iron aluminide useful as electrical resistance heating elements

    DOEpatents

    Sikka, V.K.; Deevi, S.C.; Fleischhauer, G.S.; Hajaligol, M.R.; Lilly, A.C. Jr.

    1997-04-15

    The invention relates generally to aluminum containing iron-base alloys useful as electrical resistance heating elements. The aluminum containing iron-base alloys have improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The alloy has an entirely ferritic microstructure which is free of austenite and includes, in weight %, over 4% Al, {<=}1% Cr and either {>=}0.05% Zr or ZrO{sub 2} stringers extending perpendicular to an exposed surface of the heating element or {>=}0.1% oxide dispersoid particles. The alloy can contain 14-32% Al, {<=}2% Ti, {<=}2% Mo, {<=}1% Zr, {<=}1% C, {<=}0.1% B, {<=}30% oxide dispersoid and/or electrically insulating or electrically conductive covalent ceramic particles, {<=}1% rare earth metal, {<=}1% oxygen, {<=}3% Cu, balance Fe. 64 figs.

  7. OD ESR detection of the radical anions of cyclic nitrones in liquid solutions

    NASA Astrophysics Data System (ADS)

    Barlukova, M. M.; Gritsan, N. P.; Bagryansky, V. A.; Starichenko, V. F.; Grigor'ev, I. A.; Molin, Yu. N.

    2005-01-01

    The radical anions of five-membered cyclic nitrone spin traps, 3,3,5,5-tetramethyl-1-pyrroline-1-oxide and 1,2,2,5,5-pentamethyl-3-imidazoline-3-oxide, formed under radiolysis of liquid squalane solutions at 250-268 K, were registered by the method of optically detected ESR, and the hfc constants and g-values of the radical anions were determined. The hfc constants of these radical anions were predicted by DFT calculations and were found to be in quantitative agreement with experiment. It was demonstrated that radical anions of the five-membered cyclic nitrones have non-planar geometry with the spin density localized in the C dbnd N sbnd O fragment.

  8. Transketolase counteracts oxidative stress to drive cancer development

    PubMed Central

    Xu, Iris Ming-Jing; Lai, Robin Kit-Ho; Lin, Shu-Hai; Tse, Aki Pui-Wah; Chiu, David Kung-Chun; Koh, Hui-Yu; Law, Cheuk-Ting; Wong, Chun-Ming; Cai, Zongwei; Wong, Carmen Chak-Lui; Ng, Irene Oi-Lin

    2016-01-01

    Cancer cells experience an increase in oxidative stress. The pentose phosphate pathway (PPP) is a major biochemical pathway that generates antioxidant NADPH. Here, we show that transketolase (TKT), an enzyme in the PPP, is required for cancer growth because of its ability to affect the production of NAPDH to counteract oxidative stress. We show that TKT expression is tightly regulated by the Nuclear Factor, Erythroid 2-Like 2 (NRF2)/Kelch-Like ECH-Associated Protein 1 (KEAP1)/BTB and CNC Homolog 1 (BACH1) oxidative stress sensor pathway in cancers. Disturbing the redox homeostasis of cancer cells by genetic knockdown or pharmacologic inhibition of TKT sensitizes cancer cells to existing targeted therapy (Sorafenib). Our study strengthens the notion that antioxidants are beneficial to cancer growth and highlights the therapeutic benefits of targeting pathways that generate antioxidants. PMID:26811478

  9. Synthesis, selected coordination chemistry and extraction behavior of a (phosphinoylmethyl)pyridyl N-oxide-functionalized ligand based upon a 1,4-diazepane platform

    SciTech Connect

    Ouizem, Sabrina; Rosario Amorin, Daniel; Dickie, Diane A.; Cramer, Roger E.; Campana, Charles F.; Hay, Benjamin P.; Podair, Julien; Delmau, Laetitia H.; Paine, Robert T.

    2015-05-09

    For syntheses of new multidentate chelating ligands ((6,6'4(1,4-diazepane-1,4-diyl)bis(methylene))bis(pyridine-6,2-diyl))bis(methylene))bis(diphenylphosphine oxide) (2) and 6,6'-((1,4-diazepane1,4-diyl)bis(methylene))bis(2-((diphenylphosphoryl)methyl)pyridine 1-oxide) (3), based upon a 1,4-diazepane platform functionalized with 2-(diphenylphosphinoylmethyl)pyridine P-oxide and 2-(diphenylphosphinoylmethyl)pyridine NP-dioxide fragments, respectively, the results are reported. Our results from studies of the coordination chemistry of the ligands with selected lanthanide nitrates and Cu(BF4)(2) are outlined, and crystal structures for two complexes, [Cu(2)](BF4)2 and [Cu(3)](BF4)2, are described along with survey Eu(III) and Am(III) solvent extraction analysis, for 3.

  10. Wet oxidation of AlxGa1 - xAs: Temporal evolution of composition and microstructure and the implications for metal-insulator-semiconductor applications

    NASA Astrophysics Data System (ADS)

    Ashby, Carol I. H.; Sullivan, John P.; Newcomer, Paula P.; Missert, Nancy A.; Hou, Hong Q.; Hammons, B. E.; Hafich, Michael J.; Baca, Albert G.

    1997-05-01

    Three important processes dominate the wet thermal oxidation of AlxGa1-xAs on GaAs: (1) oxidation of Al and Ga in the AlxGa1-xAs alloy to form an amorphous oxide, (2) formation and elimination of crystalline and amorphous elemental As and of amorphous As2O3, and (3) crystallization of the amorphous oxide film. Residual As can lead to strong Fermi-level pinning at the oxidized AlGaAs/GaAs interface, up to a 100-fold increase in leakage current, and a 30% increase in the dielectric constant of the oxide layer. Thermodynamically favored interfacial As may impose a fundamental limitation on the use of AlGaAs wet oxidation in metal-insulatorsemiconductor devices in the GaAs material system.

  11. Oxidants and oxidation in the Earth's atmosphere

    NASA Technical Reports Server (NTRS)

    1995-01-01

    The 1994 BOC Priestley Conference was held at Bucknell University in Lewisburg, Pennsylvania, from June 24 through June 27, 1994. This conference, managed by the American Chemical Society (ACS), was a joint celebration with the Royal Society of Chemistry (RSC) commemorating Joseph Priestley's arrival in the U.S. and his discovery of oxygen. The basic theme of the conference was 'Oxidants and Oxidation in the Earth's Atmosphere,' with a keynote lecture on the history of ozone. A distinguished group of U.S. and international atmospheric chemists addressed the issues dominating current research and policy agendas. Topics crucial to the atmospheric chemistry of global change and local and regional air pollution were discussed. The program for the conference included four technical sessions on the following topics: (1) Oxidative Fate of Atmospheric Pollutants; (2) Photochemical Smog and Ozone; (3) Stratospheric Ozone; and (4) Global Tropospheric Ozone.

  12. Synthesis, selected coordination chemistry and extraction behavior of a (phosphinoylmethyl)pyridyl N-oxide-functionalized ligand based upon a 1,4-diazepane platform

    DOE PAGES

    Ouizem, Sabrina; Rosario Amorin, Daniel; Dickie, Diane A.; Cramer, Roger E.; Campana, Charles F.; Hay, Benjamin P.; Podair, Julien; Delmau, Laetitia H.; Paine, Robert T.

    2015-05-09

    For syntheses of new multidentate chelating ligands ((6,6'4(1,4-diazepane-1,4-diyl)bis(methylene))bis(pyridine-6,2-diyl))bis(methylene))bis(diphenylphosphine oxide) (2) and 6,6'-((1,4-diazepane1,4-diyl)bis(methylene))bis(2-((diphenylphosphoryl)methyl)pyridine 1-oxide) (3), based upon a 1,4-diazepane platform functionalized with 2-(diphenylphosphinoylmethyl)pyridine P-oxide and 2-(diphenylphosphinoylmethyl)pyridine NP-dioxide fragments, respectively, the results are reported. Our results from studies of the coordination chemistry of the ligands with selected lanthanide nitrates and Cu(BF4)(2) are outlined, and crystal structures for two complexes, [Cu(2)](BF4)2 and [Cu(3)](BF4)2, are described along with survey Eu(III) and Am(III) solvent extraction analysis, for 3.

  13. Labeling Live Cells by Copper-Catalyzed Alkyne-Azide Click Chemistry

    PubMed Central

    Hong, Vu; Steinmetz, Nicole F.; Manchester, Marianne

    2010-01-01

    The copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction, optimized for biological molecules in aqueous buffers, has been shown to rapidly label mammalian cells in culture with no loss in cell viability. Metabolic uptake and display of the azide derivative of N-acetylmannosamine developed by Bertozzi, followed by CuAAC ligation using sodium ascorbate and the ligand tris(hydroxypropyltriazolyl)methylamine (THPTA), gave rise to abundant covalent attachment of dye-alkyne reactants. THPTA serves both to accelerate the CuAAC reaction and to protect the cells from damage by oxidative agents produced by the Cu-catalyzed reduction of oxygen by ascorbate, which is required to maintain the metal in the active +1 oxidation state. This procedure extends the application of this fastest of azide-based bioorthogonal reactions to the exterior of living cells. PMID:20886827

  14. Design of intrahepatocyte copper(I) chelators as drug candidates for Wilson's disease.

    PubMed

    Gateau, Christelle; Delangle, Pascale

    2014-05-01

    Wilson's disease is an autosomal recessive disease caused by mutations on the ATP7B gene found on chromosome 13. Since the corresponding ATPase is in charge of copper (Cu) distribution and excretion in the liver, its malfunctioning leads to Cu overload. This short review deals with treatments of this rare disease, which aim at decreasing Cu toxicity and are, therefore, based on chelation therapy. The drugs used since the 1950s are described first, then a novel approach developed in our laboratory is presented. Since the liver is the main organ of Cu distribution in the body, we targeted the pool of intracellular Cu in hepatocytes. This Cu pool is in the +1 oxidation state, and therefore soft sulfur ligands inspired from binding sites found in metallothioneins were developed. Their targeting to the hepatocytes by functionalization with ligands of the asialoglycoprotein receptor led to their cellular incorporation and intracellular Cu chelation.

  15. Effect of Sodium Polyanetholesulfonate on Antimicrobial Systems in Blood

    PubMed Central

    Belding, M. E.; Klebanoff, S. J.

    1972-01-01

    Sodium polyanetholesulfonate (SPS), an anticoagulant which inhibits the antimicrobial systems of blood, is used widely in blood culture media. The addition of SPS to experimental blood cultures inoculated with small numbers of a variety of organisms caused a striking increase in recovery of these organisms. Sodium fluoride also increased the incidence of positive blood cultures with some organisms. SPS completely inhibited serum antibacterial activity and serum-dependent phagocytosis (and killing) by isolated leukocytes at a concentration usually employed in blood culture media. SPS also stimulated both glucose C-1 oxidation in resting leukocytes and formate oxidation in both resting and phagocytosing leukocytes in serum-free systems. These in vitro studies support the concept that SPS is a useful additive to blood culture media and further elaborate on the mechanism of its inhibition of the microbicidal activity of blood. Images PMID:4640735

  16. Iodine Anions beyond -1: Formation of LinI (n = 2-5) and Its Interaction with Quasiatoms.

    PubMed

    Botana, Jorge; Brgoch, Jakoah; Hou, Chunju; Miao, Maosheng

    2016-09-19

    Novel phases of LinI (n = 2, 3, 4, 5) compounds are predicted to form under high pressure using first-principles density functional theory and an unbiased crystal structure search algorithm. All of the phases identified are thermodynamically stable with respect to decomposition into elemental Li and the binary LiI at a relatively low pressure (≈20 GPa). Increasing the pressure to 100 GPa yields the formation of a high pressure electride where electrons occupy interstitial quasiatom (ISQ) orbitals. Under these extreme pressures, the calculated charge on iodine suggests the oxidation state goes beyond the conventional and expected -1 charge for the halogens. This strange oxidative behavior stems from an electron transfer going from the ISQ to I(-) and Li(+) ions as high pressure collapses the void space. The resulting interplay between chemical bonding and the quantum chemical nature of enclosed interstitial space allows this first report of a halogen anion beyond a -1 oxidation state. PMID:27602431

  17. Epitaxial oxide bilayer on Pt (001) nanofacets

    NASA Astrophysics Data System (ADS)

    Hennessy, Daniel; Komanicky, Vladimir; Iddir, Hakim; Pierce, Michael S.; Menzel, Andreas; Chang, Kee-Chul; Barbour, Andi; Zapol, Peter; You, Hoydoo

    2012-01-01

    We observed an epitaxial, air-stable, partially registered (2 × 1) oxide bilayer on Pt (001) nanofacets [V. Komanicky, A. Menzel, K.-C. Chang, and H. You, J. Phys. Chem. 109, 23543 (2005)]. The bilayer is made of two half Pt layers; the top layer has four oxygen bonds and the second layer two. The positions and oxidation states of the Pt atoms are determined by analyzing crystal truncation rods and resonance scattering data. The positions of oxygen atoms are determined by density functional theory (DFT) calculations. Partial registry on the nanofacets and the absence of such registry on the extended Pt (001) surface prepared similarly are explained in DFT calculations by strain relief that can be accommodated only by nanoscale facets.

  18. Redox cycling of Fe(II) and Fe(III) in magnetite by Fe-metabolizing bacteria.

    PubMed

    Byrne, James M; Klueglein, Nicole; Pearce, Carolyn; Rosso, Kevin M; Appel, Erwin; Kappler, Andreas

    2015-03-27

    Microorganisms are a primary control on the redox-induced cycling of iron in the environment. Despite the ability of bacteria to grow using both Fe(II) and Fe(III) bound in solid-phase iron minerals, it is currently unknown whether changing environmental conditions enable the sharing of electrons in mixed-valent iron oxides between bacteria with different metabolisms. We show through magnetic and spectroscopic measurements that the phototrophic Fe(II)-oxidizing bacterium Rhodopseudomonas palustris TIE-1 oxidizes magnetite (Fe3O4) nanoparticles using light energy. This process is reversible in co-cultures by the anaerobic Fe(III)-reducing bacterium Geobacter sulfurreducens. These results demonstrate that Fe ions bound in the highly crystalline mineral magnetite are bioavailable as electron sinks and electron sources under varying environmental conditions, effectively rendering magnetite a naturally occurring battery.

  19. Stage-specific hypermutability of the regA locus of Volvox, a gene regulating the germ-soma dichotomy

    SciTech Connect

    Kirk, D.L.; Baran, G.J.; Harper, J.F.; Huskey, R.J.; Huson, K.S.; Zagris, N.

    1987-01-16

    Mutation at the regA locus confers on somatic cells of Volvox (which otherwise undergo programmed death) ability to redifferentiate as reproductive cells. Stable mutations at the regA locus, but not at other loci, were induced at high frequency when embryos at one particular stage were exposed to either UV irradiation, novobiocin, nalidixic acid, bleomycin, 4-hydroxyaminoquinoline-1-oxide, 5-bromodeoxyuridine, or 5-fluorouracil. All treatments led to some mutations that were not expressed until the second generation after treatment. The sensitive period was after somatic and reproductive cells of the next generation had been set apart, but before they had undergone cytodifferentiation. Hypermutability occurs in presumptive reproductive cells (in which regA is normally not expressed) somewhat before regA normally acts in somatic cells. We postulate that hypermutability of regA in the reproductive cells at this time reflects a change of state that the locus undergoes as it is inactivated.

  20. Oxidants and oxidation in the Earth`s atmosphere. Final technical report, 1 June 1994-30 May 1995

    SciTech Connect

    1995-02-01

    The 1994 BOC Priestley Conference was held at Bucknell University in Lewisburg, Pennsylvania, from June 24 through June 27, 1994. This conference, managed by the American Chemical Society (ACS), was a joint celebration with the Royal Society of Chemistry (RSC) commemorating Joseph Priestley`s arrival in the U.S. and his discovery of oxygen. The basic theme of the conference was `Oxidants and Oxidation in the Earth`s Atmosphere,` with a keynote lecture on the history of ozone. A distinguished group of U.S. and international atmospheric chemists addressed the issues dominating current research and policy agendas. Topics crucial to the atmospheric chemistry of global change and local and regional air pollution were discussed. The program for the conference included four technical sessions on the following topics: (1) Oxidative Fate of Atmospheric Pollutants; (2) Photochemical Smog and Ozone; (3) Stratospheric Ozone; and (4) Global Tropospheric Ozone.

  1. Urinary excretion pattern of methaqualone metabolites in man.

    PubMed

    Ericsson, O; Danielsson, B

    1977-01-01

    A method based on selected ion monitoring for determination of five monohydroxy metabolites of methaqualone in urine has been worked out. By means of this method the time course of metabolite excretion was studied in three healthy volunteers receiving an oral therapeutic dose of methaqualone. In all subjects the main monohydroxy metabolite was conjugated 4'-hydroxymethaqualone, but the relative importance of the five metabolites showed intersubject variation. Metabolite excretion was still going on, when urine sampling was discontinued after 70 hr. Only small amounts (less than 1% of the dose during 70 hr) of unmetabolized methaqualone were excreted. On the other hand, it was confirmed that methaqualone-N1-oxide is an important metabolite. The presence of a hydroxy methoxy metabolite of methaqualone, very probably 4'-hydroxy-5'-methoxymethaqualone, as a minor metabolite was established by comparison with authentic, synthetic material. 8-Hydroxymethaqualone and 2-nitrobenz-o-toluidide, reported by other groups, could not be detected.

  2. Synthesis and quantitative structure-activity relationship (QSAR) analysis of some novel oxadiazolo[3,4-d]pyrimidine nucleosides derivatives as antiviral agents.

    PubMed

    Xu, Xiaojuan; Wang, Jun; Yao, Qizheng

    2015-01-15

    We have synthesized a series of 4H,6H-[1,2,5]oxadiazolo[3,4-d]pyrimidine-5,7-dione 1-oxide nucleoside and their anti-vesicular stomatitis virus (VSV) activities in Wish cell were also investigated in vitro. It was found that most compounds showed obvious anti-VSV activities and compound 9 with ribofuranoside improved the anti-VSV activity by approximately 10 times and 18 times compared to didanosine (DDI) and acyclovir, respectively. A quantitative structure-activity relationship (QSAR) study of these compounds as well as previous reported oxadiazolo[3,4-d]pyrimidine nucleoside derivatives indicated that compounds with high activity should have small values of logP(o/w), vsurf_G and a large logS value. These findings and results provide a base for further investigations.

  3. Effects of chrysotile and acid-treated chrysotile on macrophage cultures

    PubMed Central

    Beck, E. G.; Holt, P. F.; Nasrallah, E. T.

    1971-01-01

    Beck, E. G., Holt, P. F., and Nasrallah, E. T. (1971).Brit. J. industr. Med.,28, 179-185. Effects of chrysotile and acid-treated chrysotile on macrophage cultures. The addition of chrysotile asbestos to monolayer cultures of peritoneal and alveolar macrophages produces an increase in membrane permeability, as measured by eosin uptake and lactic dehydrogenase activity of the supernatant fluid. The lactate synthesis is increased, however. It is suggested that the permeability of the cell membrane is increased while dust particles are being phagocytosed, which may take several hours when the particles are fibrous, but that this does not imply cell damage. Treatment of chrysotile with acid, which leaves a silica surface, results in a product that reduces lactate synthesis, implying cytotoxicity. This change is counteracted by poly(2-vinyl-pyridine 1-oxide). The polymer does not affect the properties of the native chrysotile. PMID:5572686

  4. Iron aluminide useful as electrical resistance heating elements

    DOEpatents

    Sikka, Vinod K.; Deevi, Seetharama C.; Fleischhauer, Grier S.; Hajaligol, Mohammad R.; Lilly, Jr., A. Clifton

    2001-01-01

    The invention relates generally to aluminum containing iron-base alloys useful as electrical resistance heating elements. The aluminum containing iron-base alloys have improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The alloy has an entirely ferritic microstructure which is free of austenite and includes, in weight %, over 4% Al, .ltoreq.1% Cr and either .gtoreq.0.05% Zr or ZrO.sub.2 stringers extending perpendicular to an exposed surface of the heating element or .gtoreq.0.1% oxide dispersoid particles. The alloy can contain 14-32% Al, .ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Zr, .ltoreq.1% C, .ltoreq.0.1% B, .ltoreq.30% oxide dispersoid and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1% rare earth metal, .ltoreq.1% oxygen, .ltoreq.3% Cu, balance Fe.

  5. Iron aluminide useful as electrical resistance heating elements

    DOEpatents

    Sikka, Vinod K.; Deevi, Seetharama C.; Fleischhauer, Grier S.; Hajaligol, Mohammad R.; Lilly, Jr., A. Clifton

    1997-01-01

    The invention relates generally to aluminum containing iron-base alloys useful as electrical resistance heating elements. The aluminum containing iron-base alloys have improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The alloy has an entirely ferritic microstructure which is free of austenite and includes, in weight %, over 4% Al, .ltoreq.1% Cr and either .gtoreq.0.05% Zr or ZrO.sub.2 stringers extending perpendicular to an exposed surface of the heating element or .gtoreq.0.1% oxide dispersoid particles. The alloy can contain 14-32% Al, .ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Zr, .ltoreq.1% C, .ltoreq.0.1% B, .ltoreq.30% oxide dispersoid and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1% rare earth metal, .ltoreq.1% oxygen, .ltoreq.3% Cu, balance Fe.

  6. Iron aluminide useful as electrical resistance heating elements

    DOEpatents

    Sikka, Vinod K.; Deevi, Seetharama C.; Fleischhauer, Grier S.; Hajaligol, Mohammad R.; Lilly, Jr., A. Clifton

    1999-01-01

    The invention relates generally to aluminum containing iron-base alloys useful as electrical resistance heating elements. The aluminum containing iron-base alloys have improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The alloy has an entirely ferritic microstructure which is free of austenite and includes, in weight %, over 4% Al, .ltoreq.1% Cr and either .gtoreq.0.05% Zr or ZrO.sub.2 stringers extending perpendicular to an exposed surface of the heating element or .gtoreq.0.1% oxide dispersoid particles. The alloy can contain 14-32% Al, .ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Zr, .ltoreq.1% C, .ltoreq.0.1% B, .ltoreq.30% oxide dispersoid and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1% rare earth metal, .ltoreq.1% oxygen, .ltoreq.3% Cu, balance Fe.

  7. Redox cycling of Fe(II) and Fe(III) in magnetite by Fe-metabolizing bacteria

    NASA Astrophysics Data System (ADS)

    Byrne, James M.; Klueglein, Nicole; Pearce, Carolyn; Rosso, Kevin M.; Appel, Erwin; Kappler, Andreas

    2015-03-01

    Microorganisms are a primary control on the redox-induced cycling of iron in the environment. Despite the ability of bacteria to grow using both Fe(II) and Fe(III) bound in solid-phase iron minerals, it is currently unknown whether changing environmental conditions enable the sharing of electrons in mixed-valent iron oxides between bacteria with different metabolisms. We show through magnetic and spectroscopic measurements that the phototrophic Fe(II)-oxidizing bacterium Rhodopseudomonas palustris TIE-1 oxidizes magnetite (Fe3O4) nanoparticles using light energy. This process is reversible in co-cultures by the anaerobic Fe(III)-reducing bacterium Geobacter sulfurreducens. These results demonstrate that Fe ions bound in the highly crystalline mineral magnetite are bioavailable as electron sinks and electron sources under varying environmental conditions, effectively rendering magnetite a naturally occurring battery.

  8. Transketolase counteracts oxidative stress to drive cancer development.

    PubMed

    Xu, Iris Ming-Jing; Lai, Robin Kit-Ho; Lin, Shu-Hai; Tse, Aki Pui-Wah; Chiu, David Kung-Chun; Koh, Hui-Yu; Law, Cheuk-Ting; Wong, Chun-Ming; Cai, Zongwei; Wong, Carmen Chak-Lui; Ng, Irene Oi-Lin

    2016-02-01

    Cancer cells experience an increase in oxidative stress. The pentose phosphate pathway (PPP) is a major biochemical pathway that generates antioxidant NADPH. Here, we show that transketolase (TKT), an enzyme in the PPP, is required for cancer growth because of its ability to affect the production of NAPDH to counteract oxidative stress. We show that TKT expression is tightly regulated by the Nuclear Factor, Erythroid 2-Like 2 (NRF2)/Kelch-Like ECH-Associated Protein 1 (KEAP1)/BTB and CNC Homolog 1 (BACH1) oxidative stress sensor pathway in cancers. Disturbing the redox homeostasis of cancer cells by genetic knockdown or pharmacologic inhibition of TKT sensitizes cancer cells to existing targeted therapy (Sorafenib). Our study strengthens the notion that antioxidants are beneficial to cancer growth and highlights the therapeutic benefits of targeting pathways that generate antioxidants. PMID:26811478

  9. Unreacted equation of states of typical energetic materials under static compression: A review

    NASA Astrophysics Data System (ADS)

    Zhaoyang, Zheng; Jijun, Zhao

    2016-07-01

    The unreacted equation of state (EOS) of energetic materials is an important thermodynamic relationship to characterize their high pressure behaviors and has practical importance. The previous experimental and theoretical works on the equation of state of several energetic materials including nitromethane, 1,3,5-trinitrohexahydro-1,3,5-triazine (RDX), 1,3,5,7-tetranitro-1,3,5,7-tetrazacyclooctane (HMX), hexanitrostilbene (HNS), hexanitrohexaazaisowurtzitane (HNIW or CL-20), pentaerythritol tetranitrate (PETN), 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105), triamino-trinitrobenzene (TATB), 1,1-diamino-2,2-dinitroethene (DADNE or FOX-7), and trinitrotoluene (TNT) are reviewed in this paper. The EOS determined from hydrostatic and non-hydrostatic compressions are discussed and compared. The theoretical results based on ab initio calculations are summarized and compared with the experimental data. Project supported by the National Natural Science Foundation of China (Grant Nos. 11174045 and 11404050).

  10. Detection of histidine oxidation in a monoclonal immunoglobulin gamma (IgG) 1 antibody.

    PubMed

    Amano, Masato; Kobayashi, Naoki; Yabuta, Masayuki; Uchiyama, Susumu; Fukui, Kiichi

    2014-08-01

    Although oxidation of methionine and tryptophan are known as popular chemical modifications that occur in monoclonal antibody (mAb) molecules, oxidation of other amino acids in mAbs has not been reported to date. In this study, oxidation of the histidine residue in a human immunoglobulin gamma (IgG) 1 molecule was discovered for the first time by mass spectrometry. The oxidation of a specific histidine located at the CH2 domain of IgG1 occurred under light stress, but it was not observed under heat stress. With the forced degradation study using several reactive oxygen species, the singlet oxygen was attributed to a reactive source of the histidine oxidation. The reaction mechanism of the histidine oxidation was proposed on the basis of the mass spectrometric analysis of IgG1 oxidized in deuterium oxide and hydrogen heavy oxide. PMID:24940720

  11. Practical use of chemical probes for reactive oxygen species produced in biological systems by γ-irradiation

    NASA Astrophysics Data System (ADS)

    Lee, Min Hee; Moon, Yu Ran; Chung, Byung Yeoup; Kim, Jae-Sung; Lee, Kang-Soo; Cho, Jae-Young; Kim, Jin-Hong

    2009-05-01

    Application of chemical probes, for detection of reactive oxygen species (ROS), was tested during γ-irradiation. The ethanol/α-(4-pyridyl-1-oxide)- N- tert-butylnitrone (4-POBN) and 3,3'-diaminobenzidine (DAB) were structurally stable enough to detect rad OH and H 2O 2, increasingly generated by γ-irradiation up to 1000 Gy. Interestingly, the production rate of H 2O 2, but not rad OH, during γ-irradiation, was significantly different between in vitro systems of lettuce and spinach. These results suggest that 4-POBN and DAB could be utilized as a semi-quantitative probe to quantify rad OH and H 2O 2, produced by γ-irradiation up to 1000 Gy.

  12. YME1L degradation reduces mitochondrial proteolytic capacity during oxidative stress

    PubMed Central

    Rainbolt, T Kelly; Saunders, Jaclyn M; Wiseman, R Luke

    2015-01-01

    Mitochondrial proteostasis is maintained by a network of ATP-dependent quality control proteases including the inner membrane protease YME1L. Here, we show that YME1L is a stress-sensitive mitochondrial protease that is rapidly degraded in response to acute oxidative stress. This degradation requires reductions in cellular ATP and involves the activity of the ATP-independent protease OMA1. Oxidative stress-dependent reductions in YME1L inhibit protective YME1L-dependent functions and increase cellular sensitivity to oxidative insult. Collectively, our results identify stress-induced YME1L degradation as a biologic process that attenuates protective regulation of mitochondrial proteostasis and promotes cellular death in response to oxidative stress. PMID:25433032

  13. Structure investigations on oxygen fluorides.

    PubMed

    Marx, Rupert; Seppelt, Konrad

    2015-12-01

    The crystal structure of O2F2 is obtained at -180 °C. In the solid state the molecule has the typical hydrogen peroxide structure that has been established long ago by electron diffraction and microwave spectroscopy. OF2 melts at -223.8 °C, so its structure is determined by powder X-ray data. The structure differs from the solid state structures of ozone and Br2O. O2F in its dissolved form as O2(+) HnFn+1(-) oxidizes palladium to the four valence state, as found some time ago. The first product formed at low temperatures is (O2(+)H3Pd2F12(-))n. PMID:26351980

  14. Homogeneous models for mechanisms of surface reactions: Propylene ammoxidation

    SciTech Connect

    Chan, D.M.T.; Nugent, W.A.; Fultz, W.C.; Rose, D.C.; Tulip, T.H.

    1987-04-01

    The proposed active sites on the catalyst surface in heterogeneous propylene ammoxidation have been successfully modelled by structurally characterized pinacolato W(VI) tert-butylimido complexes. These compounds exist as an equilibrating mixture of amine-bis(imido) and imido-bis(amido) complexes, the position of this equilibrium is dependent on the electronic nature of the glycolate ligand. Both of the C-N bond-forming reactions proposed in recent studies by Grasselli et al. (1) have been reproduced using discrete Group VI d{sup 0} organoimido complexes under mild conditions suitable for detailed mechanistic studies. These reactions are: (1) oxidative trapping of radicals at molybdenum imido sites, and (2) migration of the allyl group from oxygen to an imido nitrogen atom.

  15. The effects of surface pretreatment and nitrogen tetroxide purification on the corrosion rate of Type 304L stainless steel

    NASA Technical Reports Server (NTRS)

    Blue, G. D.; Moran, C. M.

    1985-01-01

    Corrosion rates of 304L stainless steel coupons in MON-1 oxidizer have been measured as a function of cleaning procedures employed, surface layer positions, propellant impurity levels, and short-term exposure durations (14 to 90 days). Of special interest was propellant contamination by buildup of soluble iron, which may cause flow decay. Surface treatments employed were combinations of cleaning, pickling, and passivation procedures. Propellants used were MIL-SPEC MON-1 and several types of purified NTO (i.e., low water, low chloride) which may, at a later time, be specified as spacecraft grade. Pretest coupon surface analysis by X-ray photoelectron spectroscopy (XPS-ESCA) has revealed important differences, for the different cleaning procedures, in the make-up of the surface layer, both in composition and state of chemical combination of the elements involved. Comparisons will be made of XPS/ESCA data, for different cleaning procedures, for specimens before and after propellant exposure.

  16. Isolation and Synthesis of Antiproliferative Eupolauridine Alkaloids of Ambavia gerrardii from the Madagascar Dry Forest1

    PubMed Central

    Pan, Ende; Cao, Shugeng; Brodie, Peggy J.; Callmander, Martin; Randrianaivo, Richard; Rakotonandrasana, Stephan; Rakotobe, Etienne; Rasamison, Vincent E.; TenDyke, Karen; Shen, Yongchun; Suh, Edward M.; Kingston, David G. I.

    2011-01-01

    Investigation of the Madagascan endemic plant Ambavia gerrardii (Baill.) Le Thomas (Annonaceae) for antiproliferative activity against the A2780 ovarian cancer cell line led to the isolation of the three new alkaloids 8-hydroxyeupolauridine (1), 9-methoxyeupolauridine 1-oxide (2) and 11-methoxysampangine (3), and the three known alkaloids 4–6. The structures of 1 and 2 were confirmed by synthesis. Compounds 3, 4, and 6 showed moderate to good antiproliferative activities, with IC50 values of 10.3, 3.5, and 0.60 µM, respectively, against the A2780 human ovarian cancer cell line, and with IC50 values of 0.57, 1.77, and 0.58 µM, respectively, against the H460 human lung cancer cell line. PMID:21504145

  17. Initial reactions in the oxidation of 1,2-dihydronaphthalene by Sphingomonas yanoikuyae strains.

    PubMed Central

    Eaton, S L; Resnick, S M; Gibson, D T

    1996-01-01

    The substrate oxidation profiles of Sphingomonas yanoikuyae B1 biphenyl-2,3-dioxygenase and cis-biphenyl dihydrodiol dehydrogenase activities were examined with 1,2-dihydronaphthalene and various cis-diols as substrates. m-Xylene-induced cells of strain B1 oxidized 1,2-dihydronaphthalene to (-)-(1R,2S)-cis-1,2-dihydroxy-1,2-3,4-tetrahydronaphthalene as the major product (73% relative yield). Small amounts of (+)-(R)-2-hydroxy-1,2-dihydronaphthalene (15%), naphthalene (6%), and alpha-tetralone (6%) were also formed. Strain B8/36, which lacks an active cis-biphenyl dihydrodiol dehydrogenase, formed (+)-(1R,2S)-cis-1,2-dihydroxy-1,2-dihydronaphthalene (51%), in addition to (-)-(1R,2S)-cis-1,2-dihydroxy-1,2,3,4-tetrahydronaphthalene (44%) and (+)-(R)-2-hydroxy-1,2-dihydronaphthalene (5%). The cis-biphenyl dihydrodiol dehydrogenase of strain B1 oxidized both enantiomers of cis-1,2-dihydroxy-1,2-dihydronaphthalene, but only the (+)-(1S,2R)-enantiomers of cis-1,2-dihydroxy-1,2,3,4-tetrahydronaphthalene and cis-1,2-dihydroxy-3-phenylcyclohexa-3,5-diene. The results show that biphenyl dioxygenase expressed by S. yanoikuyae catalyzes dioxygenation, monooxygenation, and desaturation reactions with 1,2-dihydronaphthalene as the substrate, and cis-biphenyl dihydrodiol dehydrogenase catalyzes the enantioselective dehydrogenation of (+)-(1S,2R)-cis-1,2-dihydroxy-1,2,3,4-tetrahydronaphthalene and (+)-(1S,2R)-cis-1,2-dihydroxy-3-phenylcyclohexa-3,5-diene. PMID:8953711

  18. One carbon metabolism in SAR11 pelagic marine bacteria.

    PubMed

    Sun, Jing; Steindler, Laura; Thrash, J Cameron; Halsey, Kimberly H; Smith, Daniel P; Carter, Amy E; Landry, Zachary C; Giovannoni, Stephen J

    2011-01-01

    The SAR11 Alphaproteobacteria are the most abundant heterotrophs in the oceans and are believed to play a major role in mineralizing marine dissolved organic carbon. Their genomes are among the smallest known for free-living heterotrophic cells, raising questions about how they successfully utilize complex organic matter with a limited metabolic repertoire. Here we show that conserved genes in SAR11 subgroup Ia (Candidatus Pelagibacter ubique) genomes encode pathways for the oxidation of a variety of one-carbon compounds and methyl functional groups from methylated compounds. These pathways were predicted to produce energy by tetrahydrofolate (THF)-mediated oxidation, but not to support the net assimilation of biomass from C1 compounds. Measurements of cellular ATP content and the oxidation of (14)C-labeled compounds to (14)CO(2) indicated that methanol, formaldehyde, methylamine, and methyl groups from glycine betaine (GBT), trimethylamine (TMA), trimethylamine N-oxide (TMAO), and dimethylsulfoniopropionate (DMSP) were oxidized by axenic cultures of the SAR11 strain Ca. P. ubique HTCC1062. Analyses of metagenomic data showed that genes for C1 metabolism occur at a high frequency in natural SAR11 populations. In short term incubations, natural communities of Sargasso Sea microbial plankton expressed a potential for the oxidation of (14)C-labeled formate, formaldehyde, methanol and TMAO that was similar to cultured SAR11 cells and, like cultured SAR11 cells, incorporated a much larger percentage of pyruvate and glucose (27-35%) than of C1 compounds (2-6%) into biomass. Collectively, these genomic, cellular and environmental data show a surprising capacity for demethylation and C1 oxidation in SAR11 cultures and in natural microbial communities dominated by SAR11, and support the conclusion that C1 oxidation might be a significant conduit by which dissolved organic carbon is recycled to CO(2) in the upper ocean. PMID:21886845

  19. Nitrone spin traps and a nitroxide antioxidant inhibit a common pathway of thymocyte apoptosis.

    PubMed Central

    Slater, A F; Nobel, C S; Maellaro, E; Bustamante, J; Kimland, M; Orrenius, S

    1995-01-01

    Oxidative stress has recently been suggested to be a mediator of apoptotic cell death [Buttke and Sandstrom (1994) Immunology Today 15, 7-10], although evidence that this phenomenon is a widespread component of apoptosis is lacking. When rat thymocytes were exposed to the glucocorticoid methylprednisolone (MPS), a progressive increase in intracellular peroxides and a decrease in glutathione (GSH) were observed to accompany the onset of apoptosis. Using Percoll density gradients to isolate subpopulations of thymocytes at different stages of apoptosis, the increase in peroxide content was found to be restricted to apoptotic cells, while a significant depletion of GSH and reduced protein thiol was detected in both pre-apoptotic and fully apoptotic cells. To investigate the biological significance of these redox changes, the free radical spin traps 5,5-dimethyl-1-pyrroline-1-oxide (DMPO) and 3,3,5,5-tetramethyl-1-pyrroline-1-oxide (TMPO), and the related nitroxide-radical antioxidant 2,2,6,6-tetramethyl-1-piperidinyl-1-oxyl (TEMPO) were tested as inhibitors of thymocyte apoptosis. The cell shrinkage and DNA fragmentation induced by four different initiators of apoptosis were reduced by each compound. TEMPO inhibition of both etoposide- and MPS-induced thymocyte DNA fragmentation was also found to correlate with an increase in intracellular GSH, providing support for the proposal that its antioxidant properties were responsible for the observed protective activity. We conclude that some form of intracellular oxidation (here measured indirectly by changes in intracellular GSH and peroxide levels) is required during thymocyte apoptosis even when this process is initiated by an agent that does not exert a direct oxidant action. Images Figure 2 Figure 4 PMID:7702573

  20. Poly(vinylpyridine oxides) in pneumoconiosis research

    PubMed Central

    Holt, P. F.

    1971-01-01

    Holt, P. F. (1971). Brit. J. industr. Med., 28, 72-77. Poly(vinylpyridine oxides) in pneumoconiosis research. Schlipköter and Brockhaus of the Institut für Lufthygiene Düsseldorf found that poly(2-vinylpyridine 1-oxide) can inhibit the fibrosis normally produced by quartz dust in the lungs or other tissues of animals. Later research in Germany and elsewhere has confirmed the earlier observations. The polymer is active when the quartz is administered by intratracheal, intraperitoneal or intravenous injection or by inhalation. It is effective if given in aqueous solution by intraperitoneal or subcutaneous injection or if it is inhaled as an aerosol. The polymer also counteracts the cytotoxic effects of finely divided quartz in cultures of alveolar or peritoneal macrophages and a rapid method for comparing the activity is based on this observation. Although some solutions of this and other polymers which show activity against quartz in cultures are less active against quartz in the whole animal, a polymer which proves inactive against quartz in cultures is invariably inactive in the whole animal. The degree of activity of this polymer depends on the molecular weight, low molecular weight being associated with low activity. Methyl groups substituted in the pyridine ring may reduce the activity or may have no effect, depending on the position of the group in the ring. The isotactic and syndiotactic forms of the polymer do not have identical effects. Poly(2-vinylpyridine 1-oxide) is not unique; poly(dimethylaminostyrene N-oxide) is almost equally effective. Several theories seek to explain the activity of this polymer against quartz but there is uncertainty, particularly because the mechanism by which silica damages cells and produces fibrosis is still in doubt. Damage to the membrane of the cell or its ultrastructures by silica has been suggested as a possible cause of cytotoxicity; it has been suggested that the polymer may shield these structures. Other suggestions

  1. MECHANISMS OF LYSOSOMAL ENZYME RELEASE FROM HUMAN LEUKOCYTES

    PubMed Central

    Zurier, Robert B.; Hoffstein, Sylvia; Weissmann, Gerald

    1973-01-01

    In order to study mechanisms underlying selective enzyme release from human leukocytes during phagocytosis, the effects were studied of compounds which affect microtubule integrity or the accumulation of cyclic nucleotides. Human leukocytes selectively extrude lysosomal enzymes (β-glucuronidase) from viable cells during phagocytosis of zymosan or immune complexes, or upon encounter with immune complexes dispersed along a non-phagocytosable surface such as a millipore filter. In each circumstance, lysosomal enzyme release was reduced by previous treatment of cells with pharmacological doses of drugs which disrupt microtubules (e.g. 10-3–10-5 M colchicine) or with agents which affect accumulation of adenosine 3'5'-monophosphate (cAMP) (e.g. 10-3 M cyclic nucleotides and 2.8 x 10-4–2.8 x 10-6 M prostaglandin E (PGE) and A (PGA) compounds). Preincubation of cells with 5 µg/ml cytochalasin B resulted in complete inhibition of zymosan ingestion, but not of adherence of zymosan particles to plasma membranes or selective enzyme release. In this system, in which enzyme release was independent of particle uptake, preincubation of cells with colchicine, vinblastine, dibutyryl cAMP, or PGE1 also reduced extrusion of lysosomal enzymes. When cell suspensions were incubated with membrane-lytic crystals of monosodium urate (MSU), cytoplasmic as well as lysosomal enzymes were released with subsequent death of the cells. However, enzyme release followed phagocytosis of crystals (as measured by enhanced C-1 oxidation of glucose) and was due to "perforation from within" of the lysosomal membrane, rather than lysis by crystals of the plasma membrane. Enzyme release after MSU ingestion was also reduced when cells were treated with pharmacological doses of the test agents. When cells were killed by Triton X-100, acting on the plasma membrane, C-1 oxidation of glucose was abolished and enzyme release could not be inhibited pharmacologically. These observations suggest that lysosomal

  2. Amino acid modified Ni catalyst exhibits reversible H2 oxidation/production over a broad pH range at elevated temperatures

    SciTech Connect

    Dutta, Arnab; DuBois, Daniel L.; Roberts, John A.; Shaw, Wendy J.

    2014-11-18

    Hydrogenases interconvert H2 and protons at high rates and with high energy efficiencies, providing inspiration for the development of molecular catalysts. Studies designed to determine how the protein scaffold can influence a catalytically active site has led to the synthesis of amino acid derivatives, [Ni(PCy2NAmino acid2)2]2+ (CyAA), of [Ni(PR2NR'2)2]2+ complexes. It is shown that these CyAA derivatives can catalyze fully reversible H2 production/oxidation, a feature reminiscent of enzymes. The reversibility is achieved in acidic aqueous solutions, 0.25% H2/Ar, and elevated temperatures (tested up to 348 K) for the glycine (CyGly), arginine (CyArg), and arginine methyl ester (CyArgOMe) derivatives. As expected for a reversible process, the activity is dependent upon H2 and proton concentration. CyArg is significantly faster in both directions than the other two derivatives (~300 s-1 H2 production and 20 s-1 H2 oxidation; pH=1, 348 K). The significantly slower rates for CyArgOMe (35 s-1 production and 7 s-1 oxidation) compared to CyArg suggests an important role for the COOH group during catalysis. That CyArg is faster than CyGly (3 s-1 production and 4 s-1 oxidation under the same conditions) suggests that the additional structural features imparted by the guanidinium groups facilitate fast and reversible H2 addition/release. These observations demonstrate that appended, outer coordination sphere amino acids work in synergy with the active site and can play an equally important role for synthetic molecular electrocatalysts as the protein scaffold does for redox active enzymes. This work was funded by the Office of Science Early Career Research Program through the US DOE, BES (AD, WJS), and the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the US DOE, BES (DLD, JASR). PNNL is operated by Battelle for the US DOE.

  3. Disorders of phospholipid metabolism: an emerging class of mitochondrial disease due to defects in nuclear genes.

    PubMed

    Lu, Ya-Wen; Claypool, Steven M

    2015-01-01

    The human nuclear and mitochondrial genomes co-exist within each cell. While the mitochondrial genome encodes for a limited number of proteins, transfer RNAs, and ribosomal RNAs, the vast majority of mitochondrial proteins are encoded in the nuclear genome. Of the multitude of mitochondrial disorders known to date, only a fifth are maternally inherited. The recent characterization of the mitochondrial proteome therefore serves as an important step toward delineating the nosology of a large spectrum of phenotypically heterogeneous diseases. Following the identification of the first nuclear gene defect to underlie a mitochondrial disorder, a plenitude of genetic variants that provoke mitochondrial pathophysiology have been molecularly elucidated and classified into six categories that impact: (1) oxidative phosphorylation (subunits and assembly factors); (2) mitochondrial DNA maintenance and expression; (3) mitochondrial protein import and assembly; (4) mitochondrial quality control (chaperones and proteases); (5) iron-sulfur cluster homeostasis; and (6) mitochondrial dynamics (fission and fusion). Here, we propose that an additional class of genetic variant be included in the classification schema to acknowledge the role of genetic defects in phospholipid biosynthesis, remodeling, and metabolism in mitochondrial pathophysiology. This seventh class includes a small but notable group of nuclear-encoded proteins whose dysfunction impacts normal mitochondrial phospholipid metabolism. The resulting human disorders present with a diverse array of pathologic consequences that reflect the variety of functions that phospholipids have in mitochondria and highlight the important role of proper membrane homeostasis in mitochondrial biology.

  4. The alkali metals: 200 years of surprises.

    PubMed

    Dye, James L

    2015-03-13

    Alkali metal compounds have been known since antiquity. In 1807, Sir Humphry Davy surprised everyone by electrolytically preparing (and naming) potassium and sodium metals. In 1808, he noted their interaction with ammonia, which, 100 years later, was attributed to solvated electrons. After 1960, pulse radiolysis of nearly any solvent produced solvated electrons, which became one of the most studied species in chemistry. In 1968, alkali metal solutions in amines and ethers were shown to contain alkali metal anions in addition to solvated electrons. The advent of crown ethers and cryptands as complexants for alkali cations greatly enhanced alkali metal solubilities. This permitted us to prepare a crystalline salt of Na(-) in 1974, followed by 30 other alkalides with Na(-), K(-), Rb(-) and Cs(-) anions. This firmly established the -1 oxidation state of alkali metals. The synthesis of alkalides led to the crystallization of electrides, with trapped electrons as the anions. Electrides have a variety of electronic and magnetic properties, depending on the geometries and connectivities of the trapping sites. In 2009, the final surprise was the experimental demonstration that alkali metals under high pressure lose their metallic character as the electrons are localized in voids between the alkali cations to become high-pressure electrides!

  5. Unraveling the interactions between cold atmospheric plasma and skin-components with vibrational microspectroscopy.

    PubMed

    Kartaschew, Konstantin; Mischo, Meike; Baldus, Sabrina; Bründermann, Erik; Awakowicz, Peter; Havenith, Martina

    2015-06-06

    Using infrared and Raman microspectroscopy, the authors examined the interaction of cold atmospheric plasma with the skin's built-in protective cushion, the outermost skin layer stratum corneum. Following a spectroscopic analysis, the authors could identify four prominent chemical alterations caused by plasma treatment: (1) oxidation of disulfide bonds in keratin leading to a generation of cysteic acid; (2) formation of organic nitrates as well as (3) of new carbonyl groups like ketones, aldehydes and acids; and (4) reduction of double bonds in the lipid matter lanolin, which resembles human sebum. The authors suggest that these generated acidic and NO-containing functional groups are the source of an antibacterial and regenerative environment at the treatment location of the stratum corneum. Based upon the author's results, the authors propose a mechanistic view of how cold atmospheric plasmas could modulate the skin chemistry to produce positive long-term effects on wound healing: briefly, cold atmospheric plasmas have the potential to transform the skin itself into a therapeutic resource.

  6. A cysteine-sulfinic acid in peroxiredoxin regulates H2O2-sensing by the antioxidant Pap1 pathway

    PubMed Central

    Vivancos, Ana P.; Castillo, Esther A.; Biteau, Benoît; Nicot, Carine; Ayté, José; Toledano, Michel B.; Hidalgo, Elena

    2005-01-01

    The Schizosaccharomyces pombe transcription factor Pap1 regulates antioxidant-gene transcription in response to H2O2. Pap1 activation occurs only at low, but not elevated, H2O2 concentrations that instead strongly trigger the mitogen-activated protein kinase Sty1 pathway. Here, we identify the peroxiredoxin Tpx1 as the upstream activator of Pap1. We show that, at low H2O2 concentrations, this oxidant scavenger can transfer a redox signal to Pap1, whereas higher concentrations of the oxidant inhibit the Tpx1-Pap1 redox relay through the temporal inactivation of Tpx1 by oxidation of its catalytic cysteine to a sulfinic acid. This cysteine modification can be reversed by the sulfiredoxin Srx1, its expression in response to high doses of H2O2 strictly depending on active Sty1. Thus, Tpx1 oxidation to the cysteine-sulfinic acid and its reversion by Srx1 constitutes a previously uncharacterized redox switch in H2O2 signaling, restricting Pap1 activation within a narrow range of H2O2 concentrations. PMID:15956211

  7. Two redox centers within Yap1 for H2O2 and thiol-reactive chemicals signaling.

    PubMed

    Azevedo, Dulce; Tacnet, Frédérique; Delaunay, Agnès; Rodrigues-Pousada, Claudina; Toledano, Michel B

    2003-10-15

    The Yap1 transcription factor regulates yeast responses to H2O2 and to several unrelated chemicals and metals. Activation by H2O2 involves Yap1 Cys303-Cys598 intra-molecular disulfide bond formation directed by the H2O2 sensor Orp1/Gpx3. We show here that the electrophile N-ethylmaleimide activates Yap1 by covalent modification of Yap1 C-terminal Cys598, Cys620, and Cys629, in an Orp1 and Yap1-oxidation-independent way, thus establishing an alternate and distinct mode of Yap1 activation. We also show that menadione, a superoxide anion generator and a highly reactive electrophile, operates both modes of Yap1 activation. Further, the Yap1 C-terminal domain reactivity towards other electrophiles (4-hydroxynonenal, iodoacetamide) and metals (cadmium, selenium) suggests a common mechanism for sensing thiol reactive chemicals, involving thiol chemical modification. We propose that Yap1 has two distinct molecular redox centers, one triggered by ROS (hydroperoxides and the superoxide anion) and the other by chemicals with thiol reactivity (electrophiles and divalent heavy metals cations). These data indicate that yeast cells cannot sense these compounds through the same molecular devices, albeit they are all electrophilic. PMID:14556853

  8. Activation of Heat Shock and Antioxidant Responses by the Natural Product Celastrol: Transcriptional Signatures of a Thiol-targeted Molecule

    PubMed Central

    Trott, Amy; West, James D.; Klaić, Lada; Westerheide, Sandy D.; Silverman, Richard B.; Morimoto, Richard I.

    2008-01-01

    Stress response pathways allow cells to sense and respond to environmental changes and adverse pathophysiological states. Pharmacological modulation of cellular stress pathways has implications in the treatment of human diseases, including neurodegenerative disorders, cardiovascular disease, and cancer. The quinone methide triterpene celastrol, derived from a traditional Chinese medicinal herb, has numerous pharmacological properties, and it is a potent activator of the mammalian heat shock transcription factor HSF1. However, its mode of action and spectrum of cellular targets are poorly understood. We show here that celastrol activates Hsf1 in Saccharomyces cerevisiae at a similar effective concentration seen in mammalian cells. Transcriptional profiling revealed that celastrol treatment induces a battery of oxidant defense genes in addition to heat shock genes. Celastrol activated the yeast Yap1 oxidant defense transcription factor via the carboxy-terminal redox center that responds to electrophilic compounds. Antioxidant response genes were likewise induced in mammalian cells, demonstrating that the activation of two major cell stress pathways by celastrol is conserved. We report that celastrol's biological effects, including inhibition of glucocorticoid receptor activity, can be blocked by the addition of excess free thiol, suggesting a chemical mechanism for biological activity based on modification of key reactive thiols by this natural product. PMID:18199679

  9. Disulfide Bond-mediated Multimerization of Ask1 and Its Reduction by Thioredoxin-1 Regulate H2O2-induced c-Jun NH2-terminal Kinase Activation and Apoptosis

    PubMed Central

    Nadeau, Philippe J.; Charette, Steve J.; Toledano, Michel B.

    2007-01-01

    Apoptosis signal-regulated kinase-1 (Ask1) lies upstream of a major redox-sensitive pathway leading to the activation of Jun NH2-terminal kinase (JNK) and the induction of apoptosis. We found that cell exposure to H2O2 caused the rapid oxidation of Ask1, leading to its multimerization through the formation of interchain disulfide bonds. Oxidized Ask1 was fully reduced within minutes after induction by H2O2. During this reduction, the thiol-disulfide oxidoreductase thioredoxin-1 (Trx1) became covalently associated with Ask1. Overexpression of Trx1 accelerated the reduction of Ask1, and a redox-inactive mutant of Trx1 (C35S) remained trapped with Ask1, blocking its reduction. Preventing the oxidation of Ask1 by either overexpressing Trx1 or using an Ask1 mutant in which the sensitive cysteines were mutated (Ask1-ΔCys) impaired the activation of JNK and the induction of apoptosis while having little effect on Ask1 activation. These results indicate that Ask1 oxidation is required at a step subsequent to activation for signaling downstream of Ask1 after H2O2 treatment. PMID:17652454

  10. Mechanistic studies on cyclohexanone oxygenase.

    PubMed

    Ryerson, C C; Ballou, D P; Walsh, C

    1982-05-25

    The bacterial flavoprotein monooxygenase carries out an oxygen insertion reaction on cyclohexanone, with ring expansion to form the seven-membered cyclic product epsilon-caprolactone, a transformation quite distinct from the phenol leads to catechol transformation carried out by the bacterial flavoprotein aromatic hydroxylases. Cyclohexanone oxygenase catalysis involves the four-electron of O2 at the expense of a two-electron oxidation of NADPH, concomitant with a two-electron oxidation of cyclohexanone to epsilon-caprolactone. NADPH oxidase activity is fully coupled with oxygen transfer to substrate. Steady-state kinetic assays demonstrate a ter-ter mechanism for this enzyme. Pre-steady-state kinetic assays demonstrate the participation of a 4a-hydroperoxyflavin intermediate during catalysis. In addition to its ketolactonizing activity, cyclohexanone oxygenase carries out S-oxygenation of thiane to thiane 1-oxide, a reaction which represents a nucleophilic displacement by the sulfur upon the terminal oxygen of the hydroperoxide. This is in contrast to cyclohexanone oxygenations where the flavin hydroperoxide acts as a nucleophile. In addition, a stable apoenzyme form is accessible and can be reconstituted with various FAD analogues with up to 100% recovery of enzyme activity. The accumulated results presented here support a Baeyer-Villiger rearrangement mechanism for the enzymatic oxygenation of cyclohexanone.

  11. PGC1α -1 Nucleosome Position and Splice Variant Expression and Cardiovascular Disease Risk in Overweight and Obese Individuals.

    PubMed

    Henagan, Tara M; Stewart, Laura K; Forney, Laura A; Sparks, Lauren M; Johannsen, Neil; Church, Timothy S

    2014-01-01

    PGC1α, a transcriptional coactivator, interacts with PPARs and others to regulate skeletal muscle metabolism. PGC1α undergoes splicing to produce several mRNA variants, with the NTPGC1α variant having a similar biological function to the full length PGC1α (FLPGC1α). CVD is associated with obesity and T2D and a lower percentage of type 1 oxidative fibers and impaired mitochondrial function in skeletal muscle, characteristics determined by PGC1α expression. PGC1α expression is epigenetically regulated in skeletal muscle to determine mitochondrial adaptations, and epigenetic modifications may regulate mRNA splicing. We report in this paper that skeletal muscle PGC1α  -1 nucleosome (-1N) position is associated with splice variant NTPGC1α but not FLPGC1α expression. Division of participants based on the -1N position revealed that those individuals with a -1N phased further upstream from the transcriptional start site (UP) expressed lower levels of NTPGC1α than those with the -1N more proximal to TSS (DN). UP showed an increase in body fat percentage and serum total and LDL cholesterol. These findings suggest that the -1N may be a potential epigenetic regulator of NTPGC1α splice variant expression, and -1N position and NTPGC1α variant expression in skeletal muscle are linked to CVD risk. This trial is registered with clinicaltrials.gov, identifier NCT00458133. PMID:25614734

  12. Production of hydroxyl radical by redox active flavonoids

    SciTech Connect

    Kalyanaraman, B.; Hodnick, W.F.; Pardini, R.S.

    1986-05-01

    The authors have previously shown that flavonoids autoxidize and generate superoxide (O/sub 2//sup -/) and hydrogen peroxide (H/sub 2/O/sub 2/), suggesting that hydroxyl radical (OH) could be formed via the metal-ion catalyzed Haber-Weiss reaction. In the presence of ethylenediamine tetraacetic acid (EDTA) and 5,5-dimethyl-1-pyrroline-1-oxide (DMPO), myricetin, quercetagetin and quercetin gave an ESR signal for the DMPO-OH spin adduct, and the DMPO-Eto adduct in the presence of excess ethanol, indicating the production of free OH. The addition of FeCl/sub 3/ to the reaction mixture resulted in a dramatic increase in the DMPO-OH signal. Without chelator (EDTA) there was no signal and the presence of diethylenetriamine-pentaacetic acid (DETAPAC) greatly diminished the signal. The presence of superoxide dismutase (SOD) had no effect on the signal while catalase completely abrogated the signal. The addition of Fe (III)-EDTA to flavonoid solutions under anaerobic conditions produced time dependent auxochromic shifts in their absorption spectra and resulted in the reduction of Fe (III) to Fe (II). These data suggest that the flavonoids autoxidize to produce O/sub 2//sup -/ and H/sub 2/O/sub 2/ by dismutation and in the presence of Fe (III)-EDTA the flavonoid can directly reduce the Fe (III) to Fe (II) resulting in the production of OH through Fenton chemistry.

  13. Indirect Oxidation of Co(II) in the Presence of the Marine Mn(II)-Oxidizing Bacterium Bacillus Sp. Strain SG-1

    SciTech Connect

    Murray, K.J.; Webb, S.M.; Bargar, J.R.; Tebo, B.M.; /Scripps Inst. Oceanography /SLAC, SSRL /Oregon Health Sci. U.

    2009-04-29

    Cobalt(II) oxidation in aquatic environments has been shown to be linked to Mn(II) oxidation, a process primarily mediated by bacteria. This work examines the oxidation of Co(II) by the spore-forming marine Mn(II)-oxidizing bacterium Bacillus sp. strain SG-1, which enzymatically catalyzes the formation of reactive nanoparticulate Mn(IV) oxides. Preparations of these spores were incubated with radiotracers and various amounts of Co(II) and Mn(II), and the rates of Mn(II) and Co(II) oxidation were measured. Inhibition of Mn(II) oxidation by Co(II) and inhibition of Co(II) oxidation by Mn(II) were both found to be competitive. However, from both radiotracer experiments and X-ray spectroscopic measurements, no Co(II) oxidation occurred in the complete absence of Mn(II), suggesting that the Co(II) oxidation observed in these cultures is indirect and that a previous report of enzymatic Co(II) oxidation may have been due to very low levels of contaminating Mn. Our results indicate that the mechanism by which SG-1 oxidizes Co(II) is through the production of the reactive nanoparticulate Mn oxide.

  14. Aluminacyclopentanes in the synthesis of 3-substituted phospholanes and α,ω-bisphospholanes.

    PubMed

    D'yakonov, Vladimir A; Makhamatkhanova, Alevtina L; Agliullina, Rina A; Dilmukhametova, Leisan K; Tyumkina, Tat'yana V; Dzhemilev, Usein M

    2016-01-01

    An efficient one-pot process for the synthesis of 3-substituted phospholanes and α,ω-bisphospholanes was developed. The method involves the replacement of aluminium in aluminacyclopentanes, prepared in situ by catalytic cycloalumination of α-olefins and α,ω-diolefins, by phosphorus atoms on treatment with dichlorophosphines (R'PCl2). Hydrogen peroxide oxidation and treatment with S8 of the synthesized phospholanes and α,ω-bisphospholanes afforded the corresponding 3-alkyl(aryl)-1-alkyl(phenyl)phospholane 1-oxides, 3-alkyl(aryl)-1-alkyl(phenyl)phospholane 1-sulfides, bisphospholane 1,1'-dioxides, and bisphospholane 1,1'-disulfides in nearly quantitative yields. The complexes LMo(CO)5 (L = 3-hexyl-1-phenylphospholane, 3-benzyl-1-methylphospholane, 1,2-bis(1-phenylphospholan-3-yl)ethane, and 1,6-bis(1-phenylphospholan-3-yl)hexane were prepared by the reaction of 3-substituted phospholanes and α,ω-bisphospholanes with molybdenum hexacarbonyl. The structure of the complexes was proved by multinuclear (1)H, (13)C, and (31)P spectroscopy. PMID:27340436

  15. A visual assay and spectrophotometric determination of LLM-105 explosive using detection of gold nanoparticle aggregation at two pH values.

    PubMed

    He, Yi; Cheng, Yang

    2016-08-01

    We report a simple, rapid, and sensitive assay for visual and spectrophotometric detection of the 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105) explosive. The assay is based on different interactions between LLM-105 and gold nanoparticle (AuNP) dispersions at two pH values, leading to the formation of dispersed or aggregated AuNPs. Two AuNP dispersions at two pH values were applied to recognize and detect LLM-105 instead of traditional AuNP dispersion under an aptotic pH to improve the anti-interference ability. The developed assay showed excellent sensitivity with a detection limit of 3 ng/mL, and the presence of as low as 0.2 μg/mL LLM-105 can be directly detected with the bare eye. This sensitivity is about six orders of magnitude higher than that of the reported traditional assays. Additionally, the assay exhibited good selectivity toward LLM-105 over other explosives, sulfur-containing compounds, and amines. Graphical abstract A simple, sensitive, and selective assay for LLM-105 was developed based on the pH-dependent interaction between the LLM-105 explosive and gold nanoparticle dispersion.

  16. Caesium in high oxidation states and as a p-block element.

    PubMed

    Miao, Mao-sheng

    2013-10-01

    The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry, rooted in the atomic shell structure. Within compounds, Group I elements, for example, invariably assume the +1 oxidation state, and their chemical properties differ completely from those of the p-block elements. These general rules govern our understanding of chemical structures and reactions. Here, first-principles calculations show that, under pressure, caesium atoms can share their 5p electrons to become formally oxidized beyond the +1 state. In the presence of fluorine and under pressure, the formation of CsF(n) (n > 1) compounds containing neutral or ionic molecules is predicted. Their geometry and bonding resemble that of isoelectronic XeF(n) molecules, showing a caesium atom that behaves chemically like a p-block element under these conditions. The calculated stability of the CsF(n) compounds shows that the inner-shell electrons can become the main components of chemical bonds.

  17. N-H⋯O versus O-H⋯O: density functional calculation and first principle molecular dynamics study on a quinoline-2-carboxamide N-oxide.

    PubMed

    Jezierska, Aneta

    2015-03-01

    N-oxide-type compounds are the object of current research interest due to the presence of resonance-assisted N-H⋯O hydrogen bonds. Here, the metric and spectroscopic parameters of N-methyl-quinoline-2-carboxamide 1-oxide were computed on the basis of density functional theory and Car-Parrinello molecular dynamics. Computations were performed in vacuo and in solid state; for both phases additional simulations with Grimme's dispersion correction were carried out. The approaches used were able to reproduce correctly the structural aspects of the studied compound and shed more light on the hydrogen bonding with special focus on bridge proton mobility. Proton transfer phenomena were found not to occur in the investigated compound, and the bridge proton was localized to the donor site. This observation is in agreement with the classical theory of the acidity of donor-acceptor sites. The presence of hydrogen bonding was confirmed using atoms-in-molecules theory. The computational results were compared with available experimental data. PMID:25690363

  18. The enhancement of oxidative DNA damage by anti-diabetic metformin, buformin, and phenformin, via nitrogen-centered radicals.

    PubMed

    Ohnishi, Shiho; Mizutani, Hideki; Kawanishi, Shosuke

    2016-08-01

    Metformin (N,N-dimethylbiguanide), buformin (1-butylbiguanide), and phenformin (1-phenethylbiguanide) are anti-diabetic biguanide drugs, expected to having anti-cancer effect. The mechanism of anti-cancer effect by these drugs is not completely understood. In this study, we demonstrated that these drugs dramatically enhanced oxidative DNA damage under oxidative condition. Metformin, buformin, and phenformin enhanced generation of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) in isolated DNA reacted with hydrogen peroxide (H2O2) and Cu(II), although these drugs did not form 8-oxodG in the absence of H2O2 or Cu(II). An electron paramagnetic resonance (EPR) study, utilizing alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone and 3,3,5,5-tetramethyl-1-pyrroline-N-oxide as spin trapping agents, showed that nitrogen-centered radicals were generated from biguanides in the presence of Cu(II) and H2O2, and that these radicals were decreased by the addition of DNA. These results suggest that biguanides enhance Cu(II)/H2O2-mediated 8-oxodG generation via nitrogen-centered radical formation. The enhancing effect on oxidative DNA damage may play a role on anti-cancer activity. PMID:27328723

  19. 7-Hydroxycoumarin modulates the oxidative metabolism, degranulation and microbial killing of human neutrophils.

    PubMed

    Kabeya, Luciana M; Fuzissaki, Carolina N; Taleb-Contini, Silvia H; da C Ferreira, Ana Maria; Naal, Zeki; Santos, Everton O L; Figueiredo-Rinhel, Andréa S G; Azzolini, Ana Elisa C S; Vermelho, Roberta B; Malvezzi, Alberto; Amaral, Antonia T-do; Lopes, João Luis C; Lucisano-Valim, Yara Maria

    2013-10-25

    In the present study, we assessed whether 7-hydroxycoumarin (umbelliferone), 7-hydroxy-4-methylcoumarin, and their acetylated analogs modulate some of the effector functions of human neutrophils and display antioxidant activity. These compounds decreased the ability of neutrophils to generate superoxide anion, release primary granule enzymes, and kill Candida albicans. Cytotoxicity did not mediate their inhibitory effect, at least under the assessed conditions. These coumarins scavenged hypochlorous acid and protected ascorbic acid from electrochemical oxidation in cell-free systems. On the other hand, the four coumarins increased the luminol-enhanced chemiluminescence of human neutrophils stimulated with phorbol-12-myristate-13-acetate and serum-opsonized zymosan. Oxidation of the hydroxylated coumarins by the neutrophil myeloperoxidase produced highly reactive coumarin radical intermediates, which mediated the prooxidant effect observed in the luminol-enhanced chemiluminescence assay. These species also oxidized ascorbic acid and the spin traps α-(4-pyridyl-1-oxide)-N-tert-butylnitrone and 5-dimethyl-1-pyrroline-N-oxide. Therefore, 7-hydroxycoumarin and the derivatives investigated here were able to modulate the effector functions of human neutrophils and scavenge reactive oxidizing species; they also generated reactive coumarin derivatives in the presence of myeloperoxidase. Acetylation of the free hydroxyl group, but not addition of the 4-methyl group, suppressed the biological effects of 7-hydroxycoumarin. These findings help clarify how 7-hydroxycoumarin acts on neutrophils to produce relevant anti-inflammatory effects. PMID:23994743

  20. Highly sensitive free radical detection by nitrone-functionalized gold nanoparticles.

    PubMed

    Du, Libo; Huang, Saipeng; Zhuang, Qianfen; Jia, Hongying; Rockenbauer, Antal; Liu, Yangping; Liu, Ke Jian; Liu, Yang

    2014-01-01

    The detection of free radicals and related species has attracted significant attention in recent years because of their critical roles in physiological and pathological processes. Among the methods for the detection of free radicals, electron spin resonance (ESR) coupled with the use of the spin trapping technique has been an effective approach for characterization and quantification of these species due to its high specificity. However, its application in biological systems, especially in in vivo systems, has been greatly limited partially due to the low reaction rate between the currently available spin traps with biological radicals. To overcome this drawback, we herein report the first example of nitrone functionalized gold nanoparticles (Au@EMPO) as highly efficient spin traps in which the thiolated EMPO (2-(ethoxycarbonyl)-2-methyl-3,4-dihydro-2H-pyrrole 1-oxide) derivative was self-assembled on gold nanoparticles. Kinetic studies showed that Au@EMPO has a 137-fold higher reaction rate constant with ˙OH than PBN (N-tert-butyl-α-phenylnitrone). Owing to the high rate of trapping ˙OH by Au@EMPO as well as the high stability of the resulting spin adduct (t½ ∼ 56 min), Au@EMPO affords 124-fold higher sensitivity for ˙OH than EMPO. Thus, this new nanospin trap shows great potential in trapping the important radicals such as ˙OH in various biological systems and provides a novel strategy to design spin traps with much improved properties. PMID:24336899

  1. The Cytochrome c Maturation Operon Is Involved in Manganese Oxidation in Pseudomonas putida GB-1

    PubMed Central

    de Vrind, J. P. M.; Brouwers, G. J.; Corstjens, P. L. A. M.; den Dulk, J.; de Vrind-de Jong, E. W.

    1998-01-01

    A Pseudomonas putida strain, strain GB-1, oxidizes Mn2+ to Mn oxide in the early stationary growth phase. It also secretes a siderophore (identified as pyoverdine) when it is subjected to iron limitation. After transposon (Tn5) mutagenesis several classes of mutants with differences in Mn2+ oxidation and/or secretion of the Mn2+-oxidizing activity were identified. Preliminary analysis of the Tn5 insertion site in one of the nonoxidizing mutants suggested that a multicopper oxidase-related enzyme is involved in Mn2+ oxidation. The insertion site in another mutant was preliminarily identified as a gene involved in the general protein secretion pathway. Two mutants defective in Mn2+-oxidizing activity also secreted porphyrins into the medium and appeared to be derepressed for pyoverdine production. These strains were chosen for detailed analysis. Both mutants were shown to contain Tn5 insertions in the ccmF gene, which is part of the cytochrome c maturation operon. They were cytochrome oxidase negative and did not contain c-type cytochromes. Complementation with part of the ccm operon isolated from the wild type restored the phenotype of the parent strain. These results indicate that a functional ccm operon is required for Mn2+ oxidation in P. putida GB-1. A possible relationship between porphyrin secretion resulting from the ccm mutation and stimulation of pyoverdine production is discussed. PMID:9758767

  2. Ternary arsenides ATt3As3 (A=K, Rb; Tt=Ge, Sn) with layered structures

    NASA Astrophysics Data System (ADS)

    Khatun, Mansura; Stoyko, Stanislav S.; Mar, Arthur

    2016-06-01

    The four ternary arsenides ATt3As3 (A=K, Rb; Tt=Ge, Sn) were obtained by reaction of the elements at 600-650 °C. They adopt an orthorhombic structure (space group Pnma, Z=4, with cell parameters ranging from a=9.9931(11) Å, b=3.7664(4) Å, c=18.607(2) Å for KGe3As3 to a=10.3211(11) Å, b=4.0917(4) Å, c=19.570(2) Å for RbSn3As3) containing corrugated [Tt3As3] layers built from Tt-centred trigonal pyramids and tetrahedra forming five-membered rings decorated with As handles. They can be considered to be Zintl phases with Tt atoms in +4, +3, and +1 oxidation states. Band structure calculations predict that these compounds are semiconductors with narrow band gaps (0.71 eV in KGe3As3, 0.50 eV in KSn3As3).

  3. Reactive oxygen species mediate cognitive deficits in experimental temporal lobe epilepsy

    PubMed Central

    Pearson, Jennifer N.; Rowley, Shane; Liang, Li-Ping; White, Andrew M.; Day, Brian J.; Patel, Manisha

    2016-01-01

    Cognitive dysfunction is an important comorbidity of temporal lobe epilepsy (TLE). However, no targeted therapies are available and the mechanisms underlying cognitive impairment, specifically deficits in learning and memory associated with TLE remain unknown. Oxidative stress is known to occur in the pathogenesis of TLE but its functional role remains to be determined. Here, we demonstrate that oxidative stress and resultant processes contribute to cognitive decline associated with epileptogenesis. Using a synthetic catalytic antioxidant, we show that pharmacological removal of reactive oxygen species (ROS) prevents 1) oxidative stress, 2) deficits in mitochondrial oxygen consumption rates, 3) hippocampal neuronal loss and 4) cognitive dysfunction without altering the intensity of the initial status epilepticus (SE) or epilepsy development in a rat model of SE-induced TLE. Moreover, the effects of the catalytic antioxidant on cognition persisted beyond the treatment period suggestive of disease-modification. The data implicate oxidative stress as a novel mechanism by which cognitive dysfunction can arise during epileptogenesis and suggest a potential disease-modifying therapeutic approach to target it. PMID:26184893

  4. Leishmanicidal Activities of Novel Synthetic Furoxan and Benzofuroxan Derivatives

    PubMed Central

    Dutra, Luiz Antônio; de Almeida, Letícia; Passalacqua, Thais G.; Reis, Juliana Santana; Torres, Fabio A. E.; Martinez, Isabel; Peccinini, Rosangela Gonçalves; Chin, Chung Man; Chegaev, Konstantin; Guglielmo, Stefano; Fruttero, Roberta

    2014-01-01

    A novel series of furoxan (1,2,5-oxadiazole 2-oxide) (compounds 3, 4a and -b, 13a and -b, and 14a to -f) and benzofuroxan (benzo[c][1,2,5]oxadiazole 1-oxide) (compounds 7 and 8a to -c) derivatives were synthesized, characterized, and evaluated for in vitro activity against promastigote and intracellular amastigote forms of Leishmania amazonensis. The furoxan derivatives exhibited the ability to generate nitric oxide at different levels (7.8% to 27.4%). The benzofuroxan derivative 8a was able to increase nitrite production in medium supernatant from murine macrophages infected with L. amazonensis at 0.75 mM after 48 h. Furoxan and benzofuroxan derivatives showed remarkable leishmanicidal activity against both promastigote and intracellular amastigote forms. Compounds 8a, 14a and -b, and 14d exerted selective leishmanicidal activities superior to those of amphotericin B and pentamidine. In vitro studies at pH 5.4 reveal that compound 8a is stable until 8 h and that compound 14a behaves as a prodrug, releasing the active aldehyde 13a. These compounds have emerged as promising novel drug candidates for the treatment of leishmaniasis. PMID:24913171

  5. Bioreactors for removing methyl bromide following contained fumigations

    USGS Publications Warehouse

    Miller, L.G.; Baesman, S.M.; Oremland, R.S.

    2003-01-01

    Use of methyl bromide (MeBr) as a quarantine, commodity, or structural fumigant is under scrutiny because its release to the atmosphere contributes to the depletion of stratospheric ozone. A closed-system bioreactor consisting of 0.5 L of a growing culture of a previously described bacterium, strain IMB-1, removed MeBr (> 110 ??mol L-1) from recirculating air. Strain IMB-1 grew slowly to high cell densities in the bioreactor using MeBr as its sole carbon and energy source. Bacterial oxidation of MeBr produced CO2 and hydrobromic acid (HBr), which required continuous neutralization with NaOH for the system to operate effectively. Strain IMB-1 was capable of sustained oxidation of large amounts of MeBr (170 mmol in 46 d). In an open-system bioreactor (10-L fermenter), strain IMB-1 oxidized a continuous supply of MeBr (220 ??mol L-1 in air). Growth was continuous, and 0.5 mol of MeBr was removed from the air supply in 14 d. The specific rate of MeBr oxidation was 7 ?? 10-16 mol cell-1 h-1. Bioreactors such as these can therefore be used to remove large quantities of contaminant MeBr, which opens the possibility of biodegradation as a practical means for its disposal.

  6. Crystal structure of domain-swapped STE20 OSR1 kinase domain

    SciTech Connect

    Lee, Seung-Jae; Cobb, Melanie H.; Goldsmith, Elizabeth J.

    2009-09-15

    OSR1 (oxidative stress-responsive-1) and SPAK (Ste20/Sps1-related proline/alanine-rich kinase) belong to the GCK-VI subfamily of Ste20 group kinases. OSR1 and SPAK are key regulators of NKCCs (Na{sup +}/K{sup +}/2Cl{sup -} cotransporters) and activated by WNK family members (with-no-lysine kinase), mutations of which are known to cause Gordon syndrome, an autosomal dominant form of inherited hypertension. The crystal structure of OSR1 kinase domain has been solved at 2.25 {angstrom}. OSR1 forms a domain-swapped dimer in an inactive conformation, in which P+1 loop and {alpha}EF helix are swapped between dimer-related monomers. Structural alignment with nonswapped Ste20 TAO2 kinase indicates that the integrity of chemical interactions in the kinase domain is well preserved in the domain-swapped interfaces. The OSR1 kinase domain has now been added to a growing list of domain-swapped protein kinases recently reported, suggesting that the domain-swapping event provides an additional layer of complexity in regulating protein kinase activity.

  7. Paraoxonase responses to exercise and niacin therapy in men with metabolic syndrome.

    PubMed

    Taylor, James Kyle; Plaisance, Eric P; Mahurin, A Jack; Mestek, Michael L; Moncada-Jimenez, Jose; Grandjean, Peter W

    2015-01-01

    Our purpose was to characterize changes in paraoxonase 1 (PON1) activity and concentration after single aerobic exercise sessions conducted before and after 6 weeks of niacin therapy in men with metabolic syndrome (MetS). Twelve men with MetS expended 500 kcal by walking at 65% of VO2max before and after a 6-week regimen of niacin. Niacin doses were titrated by 500 mg/week from 500 to 1500 mg/day and maintained at 1500 mg/day for the last 4 weeks. Fasting blood samples were collected before and 24 hours after each exercise session and analyzed for PON1 activity, PON1 concentration, myeloperoxidase (MPO), apolipoprotein A1, oxidized low-density lipoprotein (oLDL), lipoprotein particle sizes and concentrations. PON1 activity, PON1 concentration, MPO, and oLDL were unaltered following the independent effects of exercise and niacin (P > 0.05 for all). High-density lipoprotein particle size decreased by 3% (P = 0.040) and concentrations of small very low-density lipoprotein increased (P = 0.016) following exercise. PON1 activity increased 6.1% (P = 0.037) and PON1 concentrations increased 11.3% (P = 0.015) with the combination of exercise and niacin. Exercise and niacin works synergistically to increase PON1 activity and concentration with little or no changes in lipoproteins or markers of lipid oxidation.

  8. Ag{sub 2}CuMnO{sub 4}: A new silver copper oxide with delafossite structure

    SciTech Connect

    Munoz-Rojas, David; Subias, Gloria; Fraxedas, Jordi; Martinez, Benjamin; Casas-Cabanas, Montse; Canales-Vazquez, Jesus; Gonzalez-Calbet, Jose; Garcia-Gonzalez, Ester; Walton, Richard I.; Casan-Pastor, Nieves . E-mail: nieves@icmab.es

    2006-12-15

    The use of hydrothermal methods has allowed the synthesis of a new silver copper mixed oxide, Ag{sub 2}CuMnO{sub 4}, the first example of a quaternary oxide containing both elements. It crystallizes with the delafossite 3R structure, thus being the first delafossite to contain both Ag and Cu. Synthesis conditions affect the final particle size (30-500nm). Powder X-ray diffraction Rietveld refinement indicates a trigonal structure (R3-bar m) and cell parameters a=2.99991A and c=18.428A, where Cu and Mn are disordered within the octahedral B positions in the plane and linearly coordinated Ag occupies de A position between layers. X-ray absorption near edge spectroscopy (XANES) for copper and manganese, and XPS for silver evidence +2, +4, and +1 oxidation states. The microstructure consists of layered parts that may form large twins showing 5nm nanodomains. Finally, magnetic measurements reveal the existence of ferromagnetic coupling yielding in-plane moments that align antiferromagnetically at lower temperatures. The singularity of the new phase resides on the fact that is an example of a bidimensional arrangement of silver and copper in an oxide that also shows clear bidimensionality in its physical properties. That is of special relevance to the field of high T{sub c} superconducting oxides, while the ferromagnetic coupling in a bidimensional system deserves itself special attention.

  9. Argon protects against hypoxic-ischemic brain injury in neonatal rats through activation of nuclear factor (erythroid-derived 2)-like 2

    PubMed Central

    Zhao, Hailin; Mitchell, Sian; Ciechanowicz, Sarah; Savage, Sinead; Wang, Tianlong; Ji, Xunming; Ma, Daqing

    2016-01-01

    Perinatal hypoxic ischaemic encephalopathy (HIE) has a high mortality rate with neuropsychological impairment. This study investigated the neuroprotective effects of argon against neonatal hypoxic-ischaemic brain injury. In vitro cortical neuronal cell cultures derived from rat foetuses were subjected to an oxygen and glucose deprivation (OGD) challenge for 90 minutes and then exposed to 70% argon or nitrogen with 5% carbon dioxide and balanced with oxygen for 2 hours. In vivo, seven-day-old rats were subjected to unilateral common carotid artery ligation followed by hypoxic (8% oxygen balanced with nitrogen) insult for 90 minutes. They were exposed to 70% argon or nitrogen balanced with oxygen for 2 hours. In vitro, argon treatment of cortical neuronal cultures resulted in a significant increase of p-mTOR and Nuclear factor (erythroid-derived 2)-like 2(Nrf2) and protection against OGD challenge. Inhibition of m-TOR through Rapamycin or Nrf2 through siRNA abolished argon-mediated cyto-protection. In vivo, argon exposure significantly enhanced Nrf2 and its down-stream effector NAD(P)H Dehydrogenase, Quinone 1(NQO1) and superoxide dismutase 1(SOD1). Oxidative stress, neuroinflammation and neuronal cell death were significantly decreased and brain infarction was markedly reduced. Blocking PI-3K through wortmannin or ERK1/2 through U0126 attenuated argon-mediated neuroprotection. These data provide a new molecular mechanism for the potential application of argon as a neuroprotectant in HIE. PMID:27016422

  10. Aging in blood vessels. Medicinal agents FOR systemic arterial hypertension in the elderly.

    PubMed

    Rubio-Ruiz, María Esther; Pérez-Torres, Israel; Soto, María Elena; Pastelín, Gustavo; Guarner-Lans, Verónica

    2014-11-01

    Aging impairs blood vessel function and leads to cardiovascular disease. The mechanisms underlying the age-related endothelial, smooth muscle and extracellular matrix vascular dysfunction are discussed. Vascular dysfunction is caused by: (1) Oxidative stress enhancement. (2) Reduction of nitric oxide (NO) bioavailability, by diminished NO synthesis and/or augmented NO scavenging. (3) Production of vasoconstrictor/vasodilator factor imbalances. (4) Low-grade pro-inflammatory environment. (5) Impaired angiogenesis. (6) Endothelial cell senescence. The aging process in vascular smooth muscle is characterized by: (1) Altered replicating potential. (2) Change in cellular phenotype. (3) Changes in responsiveness to contracting and relaxing mediators. (4) Changes in intracellular signaling functions. Systemic arterial hypertension is an age-dependent disorder, and almost half of the elderly human population is hypertensive. The influence of hypertension on the aging cardiovascular system has been studied in models of hypertensive rats. Treatment for hypertension is recommended in the elderly. Lifestyle modifications, natural compounds and hormone therapies are useful for initial stages and as supporting treatment with medication but evidence from clinical trials in this population is needed. Since all antihypertensive agents can lower blood pressure in the elderly, therapy should be based on its potential side effects and drug interactions.

  11. Characterization of a unique [FeS] cluster in the electron transfer chain of the oxygen tolerant [NiFe] hydrogenase from Aquifex aeolicus.

    PubMed

    Pandelia, Maria-Eirini; Nitschke, Wolfgang; Infossi, Pascale; Giudici-Orticoni, Marie-Thérèse; Bill, Eckhard; Lubitz, Wolfgang

    2011-04-12

    Iron-sulfur clusters are versatile electron transfer cofactors, ubiquitous in metalloenzymes such as hydrogenases. In the oxygen-tolerant Hydrogenase I from Aquifex aeolicus such electron "wires" form a relay to a diheme cytb, an integral part of a respiration pathway for the reduction of O(2) to water. Amino acid sequence comparison with oxygen-sensitive hydrogenases showed conserved binding motifs for three iron-sulfur clusters, the nature and properties of which were unknown so far. Electron paramagnetic resonance spectra exhibited complex signals that disclose interesting features and spin-coupling patterns; by redox titrations three iron-sulfur clusters were identified in their usual redox states, a [3Fe4S] and two [4Fe4S], but also a unique high-potential (HP) state was found. On the basis of (57)Fe Mössbauer spectroscopy we attribute this HP form to a superoxidized state of the [4Fe4S] center proximal to the [NiFe] site. The unique environment of this cluster, characterized by a surplus cysteine coordination, is able to tune the redox potentials and make it compliant with the [4Fe4S](3+) state. It is actually the first example of a biological [4Fe4S] center that physiologically switches between 3+, 2+, and 1+ oxidation states within a very small potential range. We suggest that the (1 + /2+) redox couple serves the classical electron transfer reaction, whereas the superoxidation step is associated with a redox switch against oxidative stress.

  12. Expression and regulation of LOXL1 and elastin-related genes in eyes with exfoliation syndrome.

    PubMed

    Wiggs, Janey L; Pasquale, Louis R

    2014-01-01

    Variants in LOXL1 are significantly associated with exfoliation syndrome (XFS), however the impact of the associated variants on disease development is not yet understood. Initially the associated missense changes, R141L and G153D, were considered to be pathogenic alleles. Flipping of the risk allele in certain populations for both missense variants provided strong evidence that these missense changes are not biologically significant and suggest that other LOXL1 variant(s), in linkage disequilibrium with these missense variants, predispose to exfoliation syndrome by affecting gene expression or protein function. Several lines of evidence support dysregulation of LOXL1 gene expression as a contributing factor to disease development. First, in the German population the R141L (rs1048661) risk allele reduced LOXL1 expression by 20%. Second, haplotype analysis identified a risk haplotype that includes including R141L, G153D, as well as a LOXL1 promoter region variant previously shown to reduce gene expression (rs16958477). Third, the LOXL1 risk haplotype influences gene expression induced by disease-associated factors TGF-B1, oxidative stress, UV light and hypoxia. Finally, a LOXL1 null mouse has some features of XFS suggesting that decreased enzyme activity contributes to predisposition to the disease. Collectively, these results suggest that dysregulation of LOXL1 expression is a contributing factor to exfoliation disease development. PMID:25275910

  13. [Effects of ascorbic acid on the free radical formations of isoniazid and its metabolites].

    PubMed

    Matsuki, Y; Akazawa, M; Tsuchiya, K; Sakurai, H; Kiwada, H; Goromaru, T

    1991-10-01

    By the use of electron spin resonance (ESR) spectroscopy and of spin-trapping technique, the effects of ascorbic acid on the formation of the free radical intermediates due to isoniazid (INAH) and its metabolites were investigated with a microsomal system. When alpha-(4-pyridyl 1-oxide)-N-tert butylnitrone (4-POBN) was used as a spin trapping agent, the ESR signal due to hydrazine (Hy) was formed to be most intensive among others. Therefore, it was presumed that Hy is a potent intermediate to cause an INAH-induced hepatic injury. In the presence of ascorbic acid (AA), the free radical formation of Hy, INAH and acetyl hydrazine was significantly inhibited, suggesting that AA may affect the INAH-hepatitis. By the addition of inhibitors of cytochrome P-450 like metyrapone and CO, the generation of the radical from Hy decreased, confirming that the radical is formed by the cytochrome P-450 dependent microsome systems. The 4-POBN-trapped radical species generated from Hy was presumed to be the hydrazyl radical by the results of mass spectrometry.

  14. Formulation and Mechanical Properties of LLM-105 PBXs

    SciTech Connect

    Hoffman, D M; Lorenz, K T; Cunningham, B; Gagliardi, F

    2008-04-03

    Eight different polymer binders were formulated with bimodal distributions of 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105) in 5/95 weight ratio of polymer to explosive at the 25 gram level. The polymers evaluated included: Kel-F 800, Viton A, Oxy 461, Cytop A, Hyflon AD 60, Hytemp 5545, Technoflon PFR 91 and Technoflon P 459. LLM-105 had an average particle size of 35.6 {+-} 0.6 {micro}m. This material was ground in a ball mill for 24 h to achieve a particle size of 0.72 {+-} 0.02 {micro}m. Small angle light scattering measurements were used to obtain particle size distributions on both ground and unground LLM-105. Optical microscopy was used to characterize the morphology of the crystals. Bimodal mixes of approximately 75/25% coarse to fine LLM-105 were used in all formulations. Cylinders 1.27 cm diameter by 2.54 cm long were compression molded using 3 three-minute cycles at 105 C, except in the case of Cytop and Hyflon formulations which were molded at {approx}130 C. Densities varied between 94-98% of theoretical maximum. Stress strain measurements were made in compression at -30, ambient and 74 C at a strain rate of 0.0001 sec{sup -1}. As expected, the mechanical strength scaled with temperature depending on the glass transition temperature of the polymer.

  15. Phases Transition and Consolidation Mechanism of High Chromium Vanadium-Titanium Magnetite Pellet by Oxidation Process

    NASA Astrophysics Data System (ADS)

    Tang, Jue; Chu, Man-sheng; Feng, Cong; Li, Feng; Liu, Zheng-gen

    2016-08-01

    Based on the fundamental characteristics of high chromium vanadium-titanium magnetite (HCVTM), the effects of roasting temperature and roasting time on the phase transition and oxidation consolidation during the oxidation were investigated systematically. It was shown that the oxidation of HCVTM pellet was not a simple process but complex. With increasing roasting temperature and time, the compressive strength of oxidized pellet was improved. The phase transition during oxidation was hypothesized to proceed as follows: (1) Fe3O4 → Fe2O3; (2) Fe2.75Ti0.25O4 → Fe9TiO15 + FeTiO3 → Fe9TiO15 + Fe2Ti3O9; (3) Fe2VO4 → V2O3 → (Cr0.15V0.85)2O3; (4) FeCr2O4 → Cr2O3 → Cr1.3Fe0.7O3 + (Cr0.15V0.85)2O3. The oxidation consolidation process was divided into three stages: (1)oxidation below 1,173 K; (2) recrystallization consolidation at 1,173 - 1,373 K; (3) particle refining recrystallization-consolidation by the participation of liquid phase at 1,373 - 1,573 K. To obtain the HCVTM oxidized pellet with good quality, the rational roasting parameters included a roasting temperature of 1,573 K and a roasting time of 20 min.

  16. A Semi-Empirical Two Step Carbon Corrosion Reaction Model in PEM Fuel Cells

    SciTech Connect

    Young, Alan; Colbow, Vesna; Harvey, David; Rogers, Erin; Wessel, Silvia

    2013-01-01

    The cathode CL of a polymer electrolyte membrane fuel cell (PEMFC) was exposed to high potentials, 1.0 to 1.4 V versus a reversible hydrogen electrode (RHE), that are typically encountered during start up/shut down operation. While both platinum dissolution and carbon corrosion occurred, the carbon corrosion effects were isolated and modeled. The presented model separates the carbon corrosion process into two reaction steps; (1) oxidation of the carbon surface to carbon-oxygen groups, and (2) further corrosion of the oxidized surface to carbon dioxide/monoxide. To oxidize and corrode the cathode catalyst carbon support, the CL was subjected to an accelerated stress test cycled the potential from 0.6 VRHE to an upper potential limit (UPL) ranging from 0.9 to 1.4 VRHE at varying dwell times. The reaction rate constants and specific capacitances of carbon and platinum were fitted by evaluating the double layer capacitance (Cdl) trends. Carbon surface oxidation increased the Cdl due to increased specific capacitance for carbon surfaces with carbon-oxygen groups, while the second corrosion reaction decreased the Cdl due to loss of the overall carbon surface area. The first oxidation step differed between carbon types, while both reaction rate constants were found to have a dependency on UPL, temperature, and gas relative humidity.

  17. Up-Regulation of Antioxidant Proteins in the Plasma Proteome during Saturation Diving: Unique Coincidence under Hypobaric Hypoxia

    PubMed Central

    Domoto, Hideharu; Iwaya, Keiichi; Ikomi, Fumitaka; Matsuo, Hirotaka; Tadano, Yutaka; Fujii, Shigenori; Tachi, Kazuyoshi; Itoh, Yoshiyuki; Sato, Michiya; Inoue, Kimitoshi; Shinomiya, Nariyoshi

    2016-01-01

    Saturation diving (SD) is one of the safest techniques for tolerating hyperbaric conditions for long durations. However, the changes in the human plasma protein profile that occur during SD are unknown. To identify differential protein expression during or after SD, 65 blood samples from 15 healthy Japanese men trained in SD were analyzed by two-dimensional fluorescence difference gel electrophoresis. The expression of two proteins, one 32.4 kDa with an isoelectric point (pI) of 5.8 and the other 44.8 kDa with pI 4.0, were elevated during SD to 60, 100, and 200 meters sea water (msw). The expression of these proteins returned to pre-diving level when the SD training was completed. The two proteins were identified using in-gel digestion and mass spectrometric analysis; the 32.4 kDa protein was transthyretin and the 44.8 kDa protein was alpha-1-acid glycoprotein 1. Oxidation was detected at methionine 13 of transthyretin and at methionine 129 of alpha-1-acid glycoprotein 1 by tandem mass spectrometry. Moreover, haptoglobin was up-regulated during the decompression phase of 200 msw. These plasma proteins up-regulated during SD have a common function as anti-oxidants. This suggests that by coordinating their biological effects, these proteins activate a defense mechanism to counteract the effects of hyperbaric-hyperoxic conditions during SD. PMID:27741252

  18. Laparotomy in mice induces blood cell expression of inflammatory and stress genes.

    PubMed

    Ko, Fred; Isoda, Fumiko; Mobbs, Charles

    2015-04-01

    Surgical trauma induces immune and stress responses although its effects on postsurgical inflammatory and stress gene expression remain poorly characterized. This study sought to improve current scientific knowledge by investigating the effects of laparotomy on mouse blood cell inflammatory and stress gene expression. Three-month-old male C57BL/6J mice were subjected to 2% isoflurane or 2% isoflurane with laparotomy and sacrificed 4 h postintervention. Blood was collected and blood cell expression of 158 genes central to inflammatory and stress responses was assayed using quantitative polymerase chain reaction arrays. Mice subjected to isoflurane with laparotomy, compared with mice receiving isoflurane alone, had >2-fold upregulation of genes in inflammation (Osm, IL1rn, IL1b, and Csf1), oxidative stress (Hmox1), heat shock (Hspa1b), growth arrest (Cdkn1a), and DNA repair (Ugt1a2). These genes demonstrated similar expression patterns by Pearson correlation and cluster analysis. Thus, laparotomy induces coordinated, postsurgical blood cell expression of unique inflammatory and stress genes whose roles in influencing surgical outcomes need further investigation.

  19. Monooxygenase-mediated 1,2-dichloroethane degradation by Pseudomonas sp. strain DCA1

    SciTech Connect

    Hage, J.C.; Hartmans, S.

    1999-06-01

    A bacterial strain, designated Pseudomonas sp. strain DCA1, was isolated from a 1,2-dichloroethane (DCA)-degrading biofilm. Strain DCA1 utilizes DCA as the sole carbon and energy source and does not require additional organic nutrients, such as vitamins, for optimal growth. The affinity of strain DCA1 for DCA is very high, with a K{sub m} value below the detection limit of 0.5 {micro}M. Instead of a hydrolytic dehalogenation, as in other DCA utilizers, the first step in DCA degradation in strain DCA1 is an oxidation reaction. Oxygen and NAD(P)H are required for this initial step. Propene was converted to 1,2-epoxypropane by DCA-grown cells and competitively inhibited DCA degradation. The authors concluded that a monooxygenase is responsible for the first step in DCA degradation in strain DCA1. Oxidation of DCA probably results in the formation of the unstable intermediate 1,2-dichloroethanol, which spontaneously releases chloride, yielding chloroacetaldehyde. The DCA degradation pathway is strain DCA1 proceeds from chloroacetaldehyde via chloroacetic acid and presumably glycolic acid, which is similar to degradation routes observed in other DCA-utilizing bacteria.

  20. Photoinduced interactions of supramolecular ruthenium(II) complexes with plasmid DNA: synthesis and spectroscopic, electrochemical, and DNA photocleavage studies.

    PubMed

    Swavey, Shawn; DeBeer, Madeleine; Li, Kaiyu

    2015-04-01

    Two new bridging ligands have been synthesized by combining substituted benzaldehydes with phenanthrolinopyrrole (php), resulting in new polyazine bridging ligands. The ligands have been characterized by (1)H NMR, mass spectroscopy, and elemental analysis. These new ligands display π-π* transitions above 500 nm with modest molar absorptivities. Upon excitation at the ligand-centered charge-transfer transition, weak emission with a maximum wavelength of 612 nm is observed. When coordinated to two ruthenium(II) bis(bipyridyl) groups, the new bimetallic complexes generated give an overall 4+ charge. The electronic transitions of the bimetallic ruthenium(II) complexes display traditional π-π* transitions at 287 nm and metal-to-ligand charge-transfer transitions at 452 nm with molar absorptivities greater than 30000 M(-1) cm(-1). Oxidation of the ruthenium(II) metal centers to ruthenium(III) occurs at potentials above 1.4 V versus the Ag/AgCl reference electrode. Spectroscopic and electrochemical measurements indicate that the ruthenium(II) moieties behave independently. Both complexes are water-soluble and show the ability to photonick plasmid DNA when irradiated with low-energy light above 550 nm. In addition, one of the complexes, [Ru(bpy)2php]2Van(4+), shows the ability to linearize plasmid DNA and gives evidence, by gel electrophoresis, of photoinduced binding to plasmid DNA. PMID:25798576

  1. Identification, Synthesis and Evaluation of Substituted Benzofurazans as Inhibitors of CREB-mediated Gene Transcription

    PubMed Central

    Xie, Fuchun; Li, Bingbing X.; Broussard, Candice; Xiao, Xiangshu

    2013-01-01

    Cyclic-AMP response-element binding protein (CREB) is a stimulus-activated transcription factor. Its transcription activity requires its binding with CREB-binding protein (CBP) after CREB is phosphorylated at Ser133. The domains involved for CREB-CBP interaction are kinase-inducible domain (KID) from CREB and KID-interacting domain (KIX) from CBP. Recent studies suggest that CREB is an attractive target for novel cancer therapeutics. To identify novel chemotypes as inhibitors of KIX-KID interaction, we screened the NCI-diversity set of compounds using a split renilla luciferase assay and identified 2-[(7-nitrobenzo[c][1,2,5]oxadiazol-4-yl)thio]pyridine 1-oxide (compound 1) was identified as a potent inhibitor of KIX-KID interaction. However, compound 1 was not particularly selective against CREB-mediated gene transcription in living HEK 293T cells. Further structure-activity relationship studies identified 4-aniline substituted nitrobenzofurazans with improved selectivity. PMID:23953193

  2. Nontypeable Haemophilus influenzae Induces Sustained Lung Oxidative Stress and Protease Expression

    PubMed Central

    King, Paul T.; Sharma, Roleen; O’Sullivan, Kim; Selemidis, Stavros; Lim, Steven; Radhakrishna, Naghmeh; Lo, Camden; Prasad, Jyotika; Callaghan, Judy; McLaughlin, Peter; Farmer, Michael; Steinfort, Daniel; Jennings, Barton; Ngui, James; Broughton, Bradley R. S.; Thomas, Belinda; Essilfie, Ama-Tawiah; Hickey, Michael; Holmes, Peter W.; Hansbro, Philip; Bardin, Philip G.; Holdsworth, Stephen R.

    2015-01-01

    Nontypeable Haemophilus influenzae (NTHi) is a prevalent bacterium found in a variety of chronic respiratory diseases. The role of this bacterium in the pathogenesis of lung inflammation is not well defined. In this study we examined the effect of NTHi on two important lung inflammatory processes 1), oxidative stress and 2), protease expression. Bronchoalveolar macrophages were obtained from 121 human subjects, blood neutrophils from 15 subjects, and human-lung fibroblast and epithelial cell lines from 16 subjects. Cells were stimulated with NTHi to measure the effect on reactive oxygen species (ROS) production and extracellular trap formation. We also measured the production of the oxidant, 3-nitrotyrosine (3-NT) in the lungs of mice infected with this bacterium. NTHi induced widespread production of 3-NT in mouse lungs. This bacterium induced significantly increased ROS production in human fibroblasts, epithelial cells, macrophages and neutrophils; with the highest levels in the phagocytic cells. In human macrophages NTHi caused a sustained, extracellular production of ROS that increased over time. The production of ROS was associated with the formation of macrophage extracellular trap-like structures which co-expressed the protease metalloproteinase-12. The formation of the macrophage extracellular trap-like structures was markedly inhibited by the addition of DNase. In this study we have demonstrated that NTHi induces lung oxidative stress with macrophage extracellular trap formation and associated protease expression. DNase inhibited the formation of extracellular traps. PMID:25793977

  3. Nitroxides protect against peroxynitrite-induced nitration and oxidation.

    PubMed

    Sadowska-Bartosz, Izabela; Gajewska, Agnieszka; Skolimowski, Janusz; Szewczyk, Rafał; Bartosz, Grzegorz

    2015-12-01

    Nitroxides are promising compounds for prevention of undesired protein modifications. The aim of this study was to compare the efficiency of 11 nitroxides, derivatives of 2,2,6,6-tetramethylpiperidine-1-oxide (TEMPO) and 2,2,5,5-tetramethylpirrolidine-1-oxyl (PROXYL) in prevention of nitration and oxidation of model compounds and human serum albumin (HSA). Most nitroxides were very efficient in preventing loss of fluorescein fluorescence induced by peroxynitrite (PN) (IC50 in the nanomolar range) and preventing HSA nitration. The loss of fluorescein fluorescence was demonstrated to be due to nitration. Nitroxides were more effective in prevention nitration than oxidation reactions. They showed a concentration window for preventing dihydrorhodamine (DHR) 123 oxidation but exerted a prooxidant effect at both high and low concentrations. No prooxidant effect of nitroxides was seen in prevention of DHR123 oxidation induced by SIN-1. In all essays hydrophobic nitroxides (especially 4-nonylamido-TEMPO and 3-carbamolyl-dehydroPROXYL) showed the lowest efficiency. An exception was the prevention of thiol group oxidation by PN and SIN-1 where hydrophobic nitroxides were the most effective, apparently due to binding to the protein. Nitroxides showed low toxicity to MCF-7 cells. Most nitroxides, except for the most hydrophobic ones, protected cells from the cytotoxic action of SIN-1 and SIN-1-induced protein nitration. These results point to potential usefulness of nitroxides for prevention of PN-induced oxidation and, especially, nitration.

  4. 7-Hydroxycoumarin modulates the oxidative metabolism, degranulation and microbial killing of human neutrophils.

    PubMed

    Kabeya, Luciana M; Fuzissaki, Carolina N; Taleb-Contini, Silvia H; da C Ferreira, Ana Maria; Naal, Zeki; Santos, Everton O L; Figueiredo-Rinhel, Andréa S G; Azzolini, Ana Elisa C S; Vermelho, Roberta B; Malvezzi, Alberto; Amaral, Antonia T-do; Lopes, João Luis C; Lucisano-Valim, Yara Maria

    2013-10-25

    In the present study, we assessed whether 7-hydroxycoumarin (umbelliferone), 7-hydroxy-4-methylcoumarin, and their acetylated analogs modulate some of the effector functions of human neutrophils and display antioxidant activity. These compounds decreased the ability of neutrophils to generate superoxide anion, release primary granule enzymes, and kill Candida albicans. Cytotoxicity did not mediate their inhibitory effect, at least under the assessed conditions. These coumarins scavenged hypochlorous acid and protected ascorbic acid from electrochemical oxidation in cell-free systems. On the other hand, the four coumarins increased the luminol-enhanced chemiluminescence of human neutrophils stimulated with phorbol-12-myristate-13-acetate and serum-opsonized zymosan. Oxidation of the hydroxylated coumarins by the neutrophil myeloperoxidase produced highly reactive coumarin radical intermediates, which mediated the prooxidant effect observed in the luminol-enhanced chemiluminescence assay. These species also oxidized ascorbic acid and the spin traps α-(4-pyridyl-1-oxide)-N-tert-butylnitrone and 5-dimethyl-1-pyrroline-N-oxide. Therefore, 7-hydroxycoumarin and the derivatives investigated here were able to modulate the effector functions of human neutrophils and scavenge reactive oxidizing species; they also generated reactive coumarin derivatives in the presence of myeloperoxidase. Acetylation of the free hydroxyl group, but not addition of the 4-methyl group, suppressed the biological effects of 7-hydroxycoumarin. These findings help clarify how 7-hydroxycoumarin acts on neutrophils to produce relevant anti-inflammatory effects.

  5. Noble gases in oxidized residue prepared from the Saratov L4 chondrite and Raman spectroscopic study of residues to characterize phase Q

    NASA Astrophysics Data System (ADS)

    Matsuda, Jun-Ichi; Morishita, Kazuhiko; Nara, Masayuki; Amari, Sachiko

    2016-01-01

    We analyzed noble gases in an oxidized residue prepared from a HF-HCl residue of the Saratov L4 chondrite. The Ar, Kr, and Xe concentrations in the oxidized residue are two orders of magnitude lower than those in the HF-HCl residue, and they are close to concentrations in the bulk. The He and Ne concentrations are similar in the three samples. The Ne isotopic ratios are almost purely cosmogenic, indicating absence of presolar diamonds (the carrier of the HL component). Thus, Saratov contains phase Q without presolar diamond. A study of the Raman spectroscopic parameters for the HF-HCl residue and the oxidized residue shows large changes due to oxidation. The directions of these changes are the same as observed in Allende, except oxidation increased the ID/IG (intensity ratio of the D band to the G band) in Saratov but decreased in Allende. This difference may be attributed to the different crystalline stages of carbon in both meteorites. The shifts in the Raman parameters to a discrete and/or more expanded region suggest that (1) oxidation changes the crystalline condition of graphitic carbon, (2) phase Q is not a dissolved site, and (3) the release of Q-gas is simply related to the rearrangement of the carbon structure during oxidation.

  6. Chemical weathering on Mars - Thermodynamic stabilities of primary minerals /and their alteration products/ from mafic igneous rocks

    NASA Technical Reports Server (NTRS)

    Gooding, J. L.

    1978-01-01

    Chemical weathering on Mars is examined theoretically from the standpoint of thermodynamic equilibrium between primary rock-forming minerals and the atmospheric gases O2, H2O, and CO2. The primary minerals considered are those common to mafic igneous rocks and include olivine, pyroxene, plagioclase, magnetite, troilite, pyrrhotite, and apatite. The importance of kinetics and reaction mechanisms in controlling possible weathering processes on Mars is discussed within the limits of currently available data, and the possible influence of liquid water on Martian weathering processes is evaluated where appropriate. For gas-solid weathering of mafic igneous rocks at the Martian surface, it is concluded that upon attainment of thermodynamic equilibrium: (1) oxides and carbonates should dominate the mineral assemblage of weathering products; (2) hematite rather than goethite should be the stable mineral form of Fe (III); (3) FeSO4 or FeSO4.H2O could be the stable weathering product of iron sulfides in the absence of liquid water; and (4) kaolinite is apparently the only clay mineral that should be thermodynamically stable over all ranges of temperature and water-vapor abundance at the Martian surface.

  7. A phthalate family oxygenase reductase supports terpene alcohol oxidation by CYP238A1 from Pseudomonas putida KT2440.

    PubMed

    Bell, Stephen Graham; French, Laura; Rees, Nicholas Huw; Cheng, Sophia Shuyi; Preston, Gail; Wong, Luet-Lok

    2013-01-01

    CYP238A1, one of the two P450 enzymes in the genome of Pseudomonas putida KT2440, has been produced heterologously in Escherichia coli, purified, and found to bind acyclic and cyclic terpene alcohols such as farnesol, nerolidol, linalool, and terpineol. The other P450 enzyme in this organism (gene locus: PP1950) was also produced in E. coli but no substrate has been identified from a limited screen. A phthalate family oxygenase reductase (PFOR) encoded by the PP1957 gene, just downstream of the PP1955 gene for CYP238A1, accepts electrons from the reduced form of both nicotinamide adenine dinucleotide (NADH) and nicotinamide adenine dinucleotide phosphate and is able to support monooxygenase activity of CYP238A1, both in vitro and in E. coli, in which both enzymes are produced. CYP238A1 oxidizes cis- and trans-nerolidol to the 9-hydroxy product, with no evidence of attack at the olefinic double bonds. The NADH turnover rate of 170 nmol(nmol-P450)⁻¹ Min⁻¹ for CYP238A1 with cis-nerolidol as substrate at a PP1957:CYP238A1 concentration ratio of 8:1 suggests that this PFOR could function as the physiological redox partner for CYP238A1. The physiological role of CYP238A1 may be related to the PP1955 gene being part of an island/cluster of inducible genes associated with energy metabolism and response to xenobiotics. PMID:23586988

  8. Reactive oxygen species mediate cognitive deficits in experimental temporal lobe epilepsy.

    PubMed

    Pearson, Jennifer N; Rowley, Shane; Liang, Li-Ping; White, Andrew M; Day, Brian J; Patel, Manisha

    2015-10-01

    Cognitive dysfunction is an important comorbidity of temporal lobe epilepsy (TLE). However, no targeted therapies are available and the mechanisms underlying cognitive impairment, specifically deficits in learning and memory associated with TLE remain unknown. Oxidative stress is known to occur in the pathogenesis of TLE but its functional role remains to be determined. Here, we demonstrate that oxidative stress and resultant processes contribute to cognitive decline associated with epileptogenesis. Using a synthetic catalytic antioxidant, we show that pharmacological removal of reactive oxygen species (ROS) prevents 1) oxidative stress, 2) deficits in mitochondrial oxygen consumption rates, 3) hippocampal neuronal loss and 4) cognitive dysfunction without altering the intensity of the initial status epilepticus (SE) or epilepsy development in a rat model of SE-induced TLE. Moreover, the effects of the catalytic antioxidant on cognition persisted beyond the treatment period suggestive of disease-modification. The data implicate oxidative stress as a novel mechanism by which cognitive dysfunction can arise during epileptogenesis and suggest a potential disease-modifying therapeutic approach to target it.

  9. Valence State Partitioning of Cr and V Between Pyroxene - Melt: Estimates of Oxygen Fugacity for Martian Basalt QUE 94201

    NASA Technical Reports Server (NTRS)

    Karner, J. M.; Papike, J. J.; Shearer, C. K.; McKay, G.; Le, L.; Burger, P.

    2007-01-01

    Several studies, using different oxybarometers, have suggested that the variation of fO2 in martian basalts spans about 3 log units from approx. IW-1 to IW+2. The relatively oxidized basalts (e.g., pyroxene-phyric Shergotty) are enriched in incompatible elements, while the relatively reduced basalts (e.g., olivine-phyric Y980459) are depleted in incompatible elements. A popular interpretation of the above observations is that the martian mantle contains two reservoirs; 1) oxidized and enriched, and 2) reduced and depleted. The basalts are thus thought to represent mixing between these two reservoirs. Recently, Shearer et al. determined the fO2 of primitive olivine-phyric basalt Y980459 to be IW+0.9 using the partitioning of V between olivine and melt. In applying this technique to other basalts, Shearer et al. concluded that the martian mantle shergottite source was depleted and varied only slightly in fO2 (IW to IW+1). Thus the more oxidized, enriched basalts had assimilated a crustal component on their path to the martian surface. In this study we attempt to address the above debate on martian mantle fO2 using the partitioning of Cr and V into pyroxene in pyroxene-phyric basalt QUE 94201.

  10. Veratrol-O-demethylase of Acetobacterium dehalogenans: ATP-dependent reduction of the corrinoid protein.

    PubMed

    Siebert, Anke; Schubert, Torsten; Engelmann, Tina; Studenik, Sandra; Diekert, Gabriele

    2005-09-01

    The anaerobic veratrol O-demethylase mediates the transfer of the methyl group of the phenyl methyl ether veratrol to tetrahydrofolate. The primary methyl group acceptor is the cobalt of a corrinoid protein, which has to be in the +1 oxidation state to bind the methyl group. Due to the negative redox potential of the cob(II)/cob(I)alamin couple, autoxidation of the cobalt may accidentally occur. In this study, the reduction of the corrinoid to the superreduced [Co(I)] state was investigated. The ATP-dependent reduction of the corrinoid protein of the veratrol O-demethylase was shown to be dependent on titanium(III) citrate as electron donor and on an activating enzyme. In the presence of ATP, activating enzyme, and Ti(III), the redox potential versus the standard hydrogen electrode (E (SHE)) of the cob(II)alamin/cob(I)alamin couple in the corrinoid protein was determined to be -290 mV (pH 7.5), whereas E (SHE) at pH 7.5 was lower than -450 mV in the absence of either activating enzyme or ATP. ADP, AMP, or GTP could not replace ATP in the activation reaction. The ATP analogue adenosine-5'-(beta,gamma-imido)triphosphate (AMP-PNP, 2-4 mM) completely inhibited the corrinoid reduction in the presence of ATP (2 mM). PMID:15968525

  11. Doxorubicin inhibits oxidation of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) by a lactoperoxidase/H(2)O(2) system by reacting with ABTS-derived radical.

    PubMed

    Reszka, Krzysztof J; Britigan, Bradley E

    2007-10-15

    The effect of doxorubicin on oxidation of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) by lactoperoxidase and hydrogen peroxide has been investigated. It was found that: (1) oxidation of ABTS to its radical cation (ABTS*(+)) is inhibited by doxorubicin as evidenced by its induction of a lag period, duration of which depends on doxorubicin concentration; (2) the inhibition is due to doxorubicin hydroquinone reducing the ABTS*(+) radical (stoichiometry 1: 1.8); (3) concomitant with the ABTS*(+) reduction is oxidation of doxorubicin; only when the doxorubicin concentration decreases to a near zero level, net oxidation of ABTS could be detected; (4) oxidation of doxorubicin leads to its degradation to 3-methoxysalicylic acid and 3-methoxyphthalic acid; (5) the efficacy of doxorubicin to quench ABTS*(+) is similar to the efficacy of p-hydroquinone, glutathione and Trolox C. These observations support the assertion that under certain conditions doxorubicin can function as an antioxidant. They also suggest that interaction of doxorubicin with oxidants may lead to its oxidative degradation.

  12. High-temperature oxidation of Pt-45Pd-10Rh

    SciTech Connect

    Graham, G.W.; Potter, T.J.; Weber, W.H.; Gandhi, H.S.

    1988-06-01

    The surfaces of Pt-45Pd-10Rh foils oxidized over the range 875-1075 K in a 20% O/sub 2/-Ar mixture at atmospheric pressure were examined by Auger electron, X-ray photoelectron, and Raman spectroscopy. The composition of the oxide formed on the surface was found to vary with temperature from predominantly PdO at 875 K to PdRhO/sub 2/ at 1075 K. Only a few atomic percent Pt was observed, present in both the metallic and (apparently) + 1 oxidation states at 875 K and in the metallic state at 1075 K. The formation of PdRhO/sub 2/ (and no Rh/sub 2/O/sub 3/) at 1075 K was found to persist upon reoxidation following a low-temperature reduction cycle in which the increased Rh concentration on the surface was retained. An oxidation-induced Rh enrichment of the surface of the alloy foil beyond 50 at.% does not appear likely within the temperature/pressure regime investigated.

  13. Oxidation of Al-containing austenitic stainless steels as related to the formation of strong glass-ceramic to metal seals

    SciTech Connect

    Moddeman, W.E.; Birkbeck, J.C.; Bowling, W.C.; Burke, A.R.; Cassidy, R.T.

    1996-08-01

    In glass-ceramic to metal seals used in pyrotechnic actuators and ignitors, Ni-based alloys and Al-containing austenitic stainless steels are used. Metal attack by the glass is severe if Ni based alloys are used, less so for the Al-containing alloys. In this paper, lithia-alumina-silica glass-ceramic was sealed to Al-containing alloys that were first oxidized prior to sealing (preoxidation). Results show that this preoxidation substantially reduces the probability of glass/metal reactions during seal formation, thus improving the overall quality of the interface without loss of seal bond strength. Mechanism of surface oxide formation of these Al- containing steels is discussed. Auger data show the composition of the resulting oxides to be a function of oxidation temperature. There are two theories on the oxidation mechanism: (1) oxidation occurring at the air/oxide interface (Abderrazik et al, 1987), and (2) oxidation taking place at the oxide/metal interface (Hindam and Smeltzer, 1980). To test the theories, oxidation of the Al-containing alloys was carried out, first in pure oxygen-16, and then followed by pure oxygen-18. SIMS showed no layered structure, but did show a mixture of oxides. Thus, the oxidation mechanism is not simple and must be allowing oxygen to have access at all stages of the oxidation process.

  14. Disorders of phospholipid metabolism: an emerging class of mitochondrial disease due to defects in nuclear genes

    PubMed Central

    Lu, Ya-Wen; Claypool, Steven M.

    2015-01-01

    The human nuclear and mitochondrial genomes co-exist within each cell. While the mitochondrial genome encodes for a limited number of proteins, transfer RNAs, and ribosomal RNAs, the vast majority of mitochondrial proteins are encoded in the nuclear genome. Of the multitude of mitochondrial disorders known to date, only a fifth are maternally inherited. The recent characterization of the mitochondrial proteome therefore serves as an important step toward delineating the nosology of a large spectrum of phenotypically heterogeneous diseases. Following the identification of the first nuclear gene defect to underlie a mitochondrial disorder, a plenitude of genetic variants that provoke mitochondrial pathophysiology have been molecularly elucidated and classified into six categories that impact: (1) oxidative phosphorylation (subunits and assembly factors); (2) mitochondrial DNA maintenance and expression; (3) mitochondrial protein import and assembly; (4) mitochondrial quality control (chaperones and proteases); (5) iron–sulfur cluster homeostasis; and (6) mitochondrial dynamics (fission and fusion). Here, we propose that an additional class of genetic variant be included in the classification schema to acknowledge the role of genetic defects in phospholipid biosynthesis, remodeling, and metabolism in mitochondrial pathophysiology. This seventh class includes a small but notable group of nuclear-encoded proteins whose dysfunction impacts normal mitochondrial phospholipid metabolism. The resulting human disorders present with a diverse array of pathologic consequences that reflect the variety of functions that phospholipids have in mitochondria and highlight the important role of proper membrane homeostasis in mitochondrial biology. PMID:25691889

  15. Synthesis and spin-trapping properties of a new spirolactonyl nitrone.

    PubMed

    Han, Yongbin; Tuccio, Beatrice; Lauricella, Robert; Rockenbauer, Antal; Zweier, Jay L; Villamena, Frederick A

    2008-04-01

    Spin trapping using electron paramagnetic resonance (EPR) spectroscopy is commonly employed for the identification of transient radicals in chemical and biological systems. A spirolactonyl-nitrone with rigid H-bond acceptor, 7-oxa-1-azaspiro[4.4]non-1-en-6-one 1-oxide, CPCOMPO, has been synthesized and characterized, and its spin-trapping properties were investigated. The rate of formation of CPCOMPO-O2H was determined using competition kinetics between the superoxide/hydroperoxyl radical (O2*-/HO2*) trapping by CPCOMPO and the spontaneous dismutation of this radical in aqueous media. The rate constant of 60 M-1.s-1 is the highest rate constant thus far observed at neutral pH for any nitrones using the kinetic method employed. Decay kinetics were also experimentally investigated for CPCOMPO-O2H. The effect of rigid H-bond acceptor on the stability of the CPCOMPO-O2H were computationally rationalized and compared to that of EMPO-O2H, which has flexible H-bond acceptor, and results show the need of a "loose" H-bond acceptor for improved adduct stability. PMID:18331054

  16. Identification of free radical intermediates in oxidized wine using electron paramagnetic resonance spin trapping.

    PubMed

    Elias, Ryan J; Andersen, Mogens L; Skibsted, Leif H; Waterhouse, Andrew L

    2009-05-27

    Free radicals are thought to be key intermediates in the oxidation of wine, but their nature has not been established. Electron paramagnetic resonance spectroscopy was used to detect and identify several free radical species in wine under oxidative conditions with the aid of spin traps. The 1-hydroxylethyl radical was the sole radical species observed when α-(4-pyridyl-1-oxide)-N-tert-butylnitrone was used as a spin trap in a heated (55 °C), low-sulfite (15 mg L(-1)) red wine. This radical appears to arise from ethanol oxidation via the hydroxyl radical, and this latter species was confirmed by using a high concentration (1.5 M) of the 5,5-dimethylpyrroline-N-oxide spin trap, thus providing the first direct evidence of the Fenton reaction in wine. Hydroxyl radical formation in wine was corroborated by converting hydroxyl radicals to methyl radicals by its reaction with dimethyl sulfoxide. The novel spin trap 5-tert-butoxycarbonyl 5-methyl-1-pyrroline N-oxide was also used in this study to identify sulfite radicals in wine for the first time. This spin trap has also been shown to trap hydroperoxyl radicals, the generation of which is predicted in wine; however, no evidence of this species was observed. PMID:19358607

  17. Energy budget in free-living animals: a novel approach based on the doubly labeled water method.

    PubMed

    Kam, M; Degen, A A

    1997-04-01

    We provide a theoretical and practical model for the calculation of energy balance of free-living animals using the doubly labeled water method. Energy expenditure, metabolizable energy intake, and body energy balance (energy retention, negative or positive) of animals are estimated using CO2 production, water influx, and dietary habits. This model accounts for CO2 produced from the 1) oxidation of dietary substrates, 2) catabolism of body tissue, and 3) deposition of body energy. We examined the model using data from studies on five homeotherms reported in the literature. The ratios between daily energy expenditure using our model and that presented in the reports ranged between 0.76 and 1.18. Metabolizable energy intakes were as low as 43% of energy expenditure in negative energy-balanced hummingbirds and as high as 245% of energy expenditure in positive energy-balanced koala bears. This model is the first that allows theoretical calculation of all energy budget components, including energy retention, in free-living animals using the doubly labeled water method. PMID:9140038

  18. PGC1α −1 Nucleosome Position and Splice Variant Expression and Cardiovascular Disease Risk in Overweight and Obese Individuals

    PubMed Central

    Henagan, Tara M.; Stewart, Laura K.; Forney, Laura A.; Sparks, Lauren M.; Johannsen, Neil; Church, Timothy S.

    2014-01-01

    PGC1α, a transcriptional coactivator, interacts with PPARs and others to regulate skeletal muscle metabolism. PGC1α undergoes splicing to produce several mRNA variants, with the NTPGC1α variant having a similar biological function to the full length PGC1α (FLPGC1α). CVD is associated with obesity and T2D and a lower percentage of type 1 oxidative fibers and impaired mitochondrial function in skeletal muscle, characteristics determined by PGC1α expression. PGC1α expression is epigenetically regulated in skeletal muscle to determine mitochondrial adaptations, and epigenetic modifications may regulate mRNA splicing. We report in this paper that skeletal muscle PGC1α  −1 nucleosome (−1N) position is associated with splice variant NTPGC1α but not FLPGC1α expression. Division of participants based on the −1N position revealed that those individuals with a −1N phased further upstream from the transcriptional start site (UP) expressed lower levels of NTPGC1α than those with the −1N more proximal to TSS (DN). UP showed an increase in body fat percentage and serum total and LDL cholesterol. These findings suggest that the −1N may be a potential epigenetic regulator of NTPGC1α splice variant expression, and −1N position and NTPGC1α variant expression in skeletal muscle are linked to CVD risk. This trial is registered with clinicaltrials.gov, identifier NCT00458133. PMID:25614734

  19. A ¹¹C-labeled 1,4-dihydroquinoline derivative as a potential PET tracer for imaging of redox status in mouse brain.

    PubMed

    Okamura, Toshimitsu; Okada, Maki; Kikuchi, Tatsuya; Wakizaka, Hidekatsu; Zhang, Ming-Rong

    2015-12-01

    A disturbance in redox balance has been implicated in the pathogenesis of a number of diseases. This study sought to examine the feasibility of imaging brain redox status using a (11)C-labeled dihydroquinoline derivative ([(11)C]DHQ1) for positron emission tomography (PET). The lipophilic PET tracer [(11)C]DHQ1 was rapidly oxidized to its hydrophilic form in mouse brain homogenate. The redox modulators diphenyleneiodonium and apocynin significantly reduced the initial velocity of [(11)C]DHQ1 oxidation, and apocynin also caused concentration-dependent inhibition of the initial velocity. Moreover, [(11)C]DHQ1 readily entered the brain by diffusion after administration and underwent oxidation into the hydrophilic cationic form, which then slowly decreased. By contrast, apocynin treatment inhibited the in vivo oxidation of [(11)C]DHQ1 to the hydrophilic cationic form, leading to a rapid decrease of radioactivity in the brain. Thus, the difference in the [(11)C]DHQ1 kinetics reflects the alteration in redox status caused by apocynin. In conclusion, [(11)C]DHQ1 is a potential PET tracer for imaging of redox status in the living brain.

  20. Method and reaction pathway for selectively oxidizing organic compounds

    DOEpatents

    Camaioni, Donald M.; Lilga, Michael A.

    1998-01-01

    A method of selectively oxidizing an organic compound in a single vessel comprises: a) combining an organic compound, an acid solution in which the organic compound is soluble, a compound containing two oxygen atoms bonded to one another, and a metal ion reducing agent capable of reducing one of such oxygen atoms, and thereby forming a mixture; b) reducing the compound containing the two oxygen atoms by reducing one of such oxygen atoms with the metal ion reducing agent to, 1) oxidize the metal ion reducing agent to a higher valence state, and 2) produce an oxygen containing intermediate capable of oxidizing the organic compound; c) reacting the oxygen containing intermediate with the organic compound to oxidize the organic compound into an oxidized organic intermediate, the oxidized organic intermediate having an oxidized carbon atom; d) reacting the oxidized organic intermediate with the acid counter ion and higher valence state metal ion to bond the acid counter ion to the oxidized carbon atom and thereby produce a quantity of an ester incorporating the organic intermediate and acid counter ion; and e) reacting the oxidized organic intermediate with the higher valence state metal ion and water to produce a quantity of alcohol which is less than the quantity of ester, the acid counter ion incorporated in the ester rendering the carbon atom bonded to the counter ion less reactive with the oxygen containing intermediate in the mixture than is the alcohol with the oxygen containing intermediate.

  1. Reactive oxygen species mediate cognitive deficits in experimental temporal lobe epilepsy.

    PubMed

    Pearson, Jennifer N; Rowley, Shane; Liang, Li-Ping; White, Andrew M; Day, Brian J; Patel, Manisha

    2015-10-01

    Cognitive dysfunction is an important comorbidity of temporal lobe epilepsy (TLE). However, no targeted therapies are available and the mechanisms underlying cognitive impairment, specifically deficits in learning and memory associated with TLE remain unknown. Oxidative stress is known to occur in the pathogenesis of TLE but its functional role remains to be determined. Here, we demonstrate that oxidative stress and resultant processes contribute to cognitive decline associated with epileptogenesis. Using a synthetic catalytic antioxidant, we show that pharmacological removal of reactive oxygen species (ROS) prevents 1) oxidative stress, 2) deficits in mitochondrial oxygen consumption rates, 3) hippocampal neuronal loss and 4) cognitive dysfunction without altering the intensity of the initial status epilepticus (SE) or epilepsy development in a rat model of SE-induced TLE. Moreover, the effects of the catalytic antioxidant on cognition persisted beyond the treatment period suggestive of disease-modification. The data implicate oxidative stress as a novel mechanism by which cognitive dysfunction can arise during epileptogenesis and suggest a potential disease-modifying therapeutic approach to target it. PMID:26184893

  2. Pro-oxidative interactions of cobalt with human neutrophils.

    PubMed

    Ramafi, Grace J; Theron, Annette J; Anderson, Ronald

    2004-08-01

    The primary objectives of this study were to investigate the effects of cobalt(II) chloride (Co, 1.5-25 microM) on the reactivity of hydrogen peroxide (H2O2, 100 microM) or oxidants generated by activated human neutrophils. The prooxidative interactions of Co with H2O2 or cells were measured by luminol-enhanced chemiluminescence (LECL), and according to the extent of oxidative inactivation of added alpha-1-proteinase inhibitor (API). Cobalt dramatically potentiated the oxidation of luminol and API by both H2O2 and neutrophils activated with phorbol 12-myristate 13-acetate (5 ng/ml), without affecting the assembly of NADPH oxidase or the magnitude of oxygen consumption by the cells. Using 5,5-dimethyl-pyrolline 1-oxide-based electron spin resonance spectroscopy we were unable to detect hydroxyl radical formation by Co in the presence of either H2O2 or activated neutrophils, while the corresponding LECL responses were unaffected by the hydroxyl radical scavengers benzoate and mannitol (50 mM). These observations indicate that Co potentiates the reactivity of neutrophil-derived oxidants, primarily H2O2, which if operative in vivo during exposure to the heavy metal may pose the risk of oxidant- and protease-mediated tissue injury.

  3. The alkali metals: 200 years of surprises.

    PubMed

    Dye, James L

    2015-03-13

    Alkali metal compounds have been known since antiquity. In 1807, Sir Humphry Davy surprised everyone by electrolytically preparing (and naming) potassium and sodium metals. In 1808, he noted their interaction with ammonia, which, 100 years later, was attributed to solvated electrons. After 1960, pulse radiolysis of nearly any solvent produced solvated electrons, which became one of the most studied species in chemistry. In 1968, alkali metal solutions in amines and ethers were shown to contain alkali metal anions in addition to solvated electrons. The advent of crown ethers and cryptands as complexants for alkali cations greatly enhanced alkali metal solubilities. This permitted us to prepare a crystalline salt of Na(-) in 1974, followed by 30 other alkalides with Na(-), K(-), Rb(-) and Cs(-) anions. This firmly established the -1 oxidation state of alkali metals. The synthesis of alkalides led to the crystallization of electrides, with trapped electrons as the anions. Electrides have a variety of electronic and magnetic properties, depending on the geometries and connectivities of the trapping sites. In 2009, the final surprise was the experimental demonstration that alkali metals under high pressure lose their metallic character as the electrons are localized in voids between the alkali cations to become high-pressure electrides! PMID:25666067

  4. Interaction of recombinant octameric hemoglobin with endothelial cells.

    PubMed

    Gaucher, Caroline; Domingues-Hamdi, Élisa; Prin-Mathieu, Christine; Menu, Patrick; Baudin-Creuza, Véronique

    2015-02-01

    Hemoglobin-based oxygen carriers (HBOCs) may generate oxidative stress, vasoconstriction and inflammation. To reduce these undesirable vasoactive properties, we increased hemoglobin (Hb) molecular size by genetic engineering with octameric Hb, recombinant (r) HbβG83C. We investigate the potential side effects of rHbβG83C on endothelial cells. The rHbβG83C has no impact on cell viability, and induces a huge repression of endothelial nitric oxide synthase gene transcription, a marker of vasomotion. No induction of Intermolecular-Adhesion Molecule 1 and E-selectin (inflammatory markers) transcription was seen. In the presence of rHbβG83C, the transcription of heme oxygenase-1 (oxidative stress marker) is weakly increased compared to the two other HBOCs (references) or Voluven (control). This genetically engineered octameric Hb, based on a human Hb βG83C mutant, leads to little impact at the level of endothelial cell inflammatory response and thus appears as an interesting molecule for HBOC development.

  5. Development of oxide fibrous monolith systems.

    SciTech Connect

    Goretta, K. C.

    1999-03-02

    Fibrous monolithic ceramics generally have a cellular structure that consists of a strong cell surrounded by a weaker boundary phase [1-5]. Fibrous monoliths (FMs) are produced from powders by conventional ceramic fabrication techniques, such as extrusion [1,2]. When properly engineered, they exhibit fail gracefully [3-5]. Several compositions of ceramics and cermets have been processed successfully in fibrous monolithic form [4]. The most thoroughly investigated fibrous monolith consists of Si{sub 3}N{sub 4} cells and a BN cell-boundary phase [3-5]. Through appropriate selection of initial powders and extrusion and hot-pressing parameters, very tough final products have been produced. The resultant high toughness is due primarily to delamination during fracture along textured platelike BN grains. The primary objectives of our program are to develop: (1) Oxide-based FMs, including new systems with improved properties; (2) FMs that can be pressureless sintered rather than hot-pressed; (3) Techniques for continuous extrusion of FM filaments, including solid freeform fabrication (SFF) for net-shape fabrication of FMs; (4) Predictive micromechanical models for FM design and performance; and (5) Ties with industrial producers and users of FMs.

  6. Gallium Zeolites for Light Paraffin Aromatization

    SciTech Connect

    Price, G.L.; Dooley, K.M.

    1999-02-10

    The primary original goal of this project was to investigate the active state of gallium-containing MFI catalysts for light paraffin aromatization, in particular the state of gallium in the active material. Our original hypothesis was that the most active and selective materials were those which contained gallium zeolitic cations, and that previously reported conditions for the activation of gallium-containing catalysts served to create these active centers. We believed that in high silica materials such as MFI, ion-exchange is most effectively accomplished with metals in their 1+ oxidation state, both because of the sparsity of the anionic ion-exchange sites associated with the zeolite, and because the large hydration shells associated with aqueous 3+ cations hinder transport. Metals such as Ga which commonly exist in higher oxidation states need to be reduced to promote ion-exchange and this is the reason that reduction of gallium-containing catalysts for light paraffin aromatization often yields a dramatic enhancement in catalytic activity. We have effectively combined reduction with ion-exchange and we term this combined process ''reductive solid-state ion-exchange''. Our hypothesis has largely been proven true, and a number of the papers we have published directly address this hypothesis.

  7. Unraveling the interactions between cold atmospheric plasma and skin-components with vibrational microspectroscopy.

    PubMed

    Kartaschew, Konstantin; Mischo, Meike; Baldus, Sabrina; Bründermann, Erik; Awakowicz, Peter; Havenith, Martina

    2015-01-01

    Using infrared and Raman microspectroscopy, the authors examined the interaction of cold atmospheric plasma with the skin's built-in protective cushion, the outermost skin layer stratum corneum. Following a spectroscopic analysis, the authors could identify four prominent chemical alterations caused by plasma treatment: (1) oxidation of disulfide bonds in keratin leading to a generation of cysteic acid; (2) formation of organic nitrates as well as (3) of new carbonyl groups like ketones, aldehydes and acids; and (4) reduction of double bonds in the lipid matter lanolin, which resembles human sebum. The authors suggest that these generated acidic and NO-containing functional groups are the source of an antibacterial and regenerative environment at the treatment location of the stratum corneum. Based upon the author's results, the authors propose a mechanistic view of how cold atmospheric plasmas could modulate the skin chemistry to produce positive long-term effects on wound healing: briefly, cold atmospheric plasmas have the potential to transform the skin itself into a therapeutic resource. PMID:25947390

  8. Photosynthetic reaction centers in bacteria

    SciTech Connect

    Norris, J.R. Univ. of Chicago, IL ); Schiffer, M. )

    1990-07-30

    The photochemistry of photosynthesis begins in complexes called reaction centers. These have become model systems to study the fundamental process by which plants and bacteria convert and store solar energy as chemical free energy. In green plants, photosynthesis occurs in two systems, each of which contains a different reaction center, working in series. In one, known as photosystem 1, oxidized nicotinamide adenine dinucleotide phosphate (NADP[sup +]) is reduced to NADPH for use in a series of dark reactions called the Calvin cycle, named for Nobel Laureate Melvin Calvin, by which carbon dioxide is converted into useful fuels such as carbohydrates and sugars. In the other half of the photosynthetic machinery of green plants, called photosystem 2, water is oxidized to produce molecular oxygen. A different form of photosynthesis occurs in photosynthetic bacteria, which typically live at the bottom of ponds and feed on organic debris. Two main types of photosynthetic bacteria exist: purple and green. Neither type liberates oxygen from water. Instead, the bacteria feed on organic media or inorganic materials, such as sulfides, which are easier to reduce or oxidize than carbon dioxide or water. Perhaps in consequence, their photosynthetic machinery is simpler than that of green, oxygen-evolving plants and their primary photochemistry is better understood.

  9. Laparotomy in Mice Induces Blood Cell Expression of Inflammatory and Stress Genes

    PubMed Central

    Isoda, Fumiko; Mobbs, Charles

    2015-01-01

    Surgical trauma induces immune and stress responses although its effects on postsurgical inflammatory and stress gene expression remain poorly characterized. This study sought to improve current scientific knowledge by investigating the effects of laparotomy on mouse blood cell inflammatory and stress gene expression. Three-month-old male C57BL/6J mice were subjected to 2% isoflurane or 2% isoflurane with laparotomy and sacrificed 4 h postintervention. Blood was collected and blood cell expression of 158 genes central to inflammatory and stress responses was assayed using quantitative polymerase chain reaction arrays. Mice subjected to isoflurane with laparotomy, compared with mice receiving isoflurane alone, had >2-fold upregulation of genes in inflammation (Osm, IL1rn, IL1b, and Csf1), oxidative stress (Hmox1), heat shock (Hspa1b), growth arrest (Cdkn1a), and DNA repair (Ugt1a2). These genes demonstrated similar expression patterns by Pearson correlation and cluster analysis. Thus, laparotomy induces coordinated, postsurgical blood cell expression of unique inflammatory and stress genes whose roles in influencing surgical outcomes need further investigation. PMID:25406893

  10. Diode-less bilayer oxide (WO(x)-NbO(x)) device for cross-point resistive memory applications.

    PubMed

    Liu, Xinjun; Sadaf, Sharif Md; Son, Myungwoo; Shin, Jungho; Park, Jubong; Lee, Joonmyoung; Park, Sangsu; Hwang, Hyunsang

    2011-11-25

    The combination of a threshold switching device and a resistive switching (RS) device was proposed to suppress the undesired sneak current for the integration of bipolar RS cells in a cross-point array type memory. A simulation for this hybrid-type device shows that the matching of key parameters between switch element and memory element is an important issue. Based on the threshold switching oxides, a conceptual structure with a simple metal-oxide 1-oxide 2-metal stack was provided to accommodate the evolution trend. We show that electroformed W-NbO(x)-Pt devices can simultaneously exhibit both threshold switching and memory switching. A qualitative model was suggested to elucidate the unique properties in a W-NbO(x)-Pt stack, where threshold switching is associated with a localized metal-insulator transition in the NbO(x) bulk, and the bipolar RS derives from a redox at the tip of the localized filament at the WO(x)-NbO(x) interface. Such a simple metal-oxide-metal structure, with functionally separated bulk and interface effects, provides a fabrication advantage for future high-density cross-point memory devices.

  11. Study on biodegradation process of lignin by FTIR and DSC.

    PubMed

    Liu, Yang; Hu, Tianjue; Wu, Zhengping; Zeng, Guangming; Huang, Danlian; Shen, Ying; He, Xiaoxiao; Lai, Mingyong; He, Yibin

    2014-12-01

    The biodegradation process of lignin by Penicillium simplicissimum was studied to reveal the lignin biodegradation mechanisms. The biodegradation products of lignin were detected using Fourier transform infrared spectroscopy (FTIR), UV-Vis spectrophotometer, different scanning calorimeter (DSC), and stereoscopic microscope. The analysis of FTIR spectrum showed the cleavage of various ether linkages (1,365 and 1,110 cm(-1)), oxidation, and demethylation (2,847 cm(-1)) by comparing the different peak values in the corresponding curve of each sample. Moreover, the differences (Tm and ΔHm values) between the DSC curves indirectly verified the FTIR analysis of biodegradation process. In addition, the effects of adding hydrogen peroxide (H2O2) to lignin biodegradation process were analyzed, which indicated that H2O2 could accelerate the secretion of the MnP and LiP and improve the enzymes activity. What is more, lignin peroxidase and manganese peroxidase catalyzed the lignin degradation effectively only when H2O2 was presented.

  12. Free radicals from 1-palmitoyl-2-arachidonoylphosphatidylcholine liposomes in Fe2+/ascorbic acid solution.

    PubMed

    Yoshida, T; Otake, H; Aramaki, Y; Hara, T; Tsuchiya, S; Hamada, A; Utsumi, H

    1996-06-01

    The generation of free radicals during the lipid peroxidation of liposomes composed of 1-palmitoyl-2-arachidonoylphosphatidylcholine (PAPC-liposome) in Fe2+/ascorbic acid (AsA) solution was studied by the ESR spin trapping technique. A carbon-centered radical adduct was observed using alpha-(4-pyridyl-1-oxide)-N-tert-butyl-nitorone (4-POBN) and 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), but no oxygen-centered radicals such as .OH, LO., and LOO. were observed. The lipid peroxidation evaluated as 2-thiobarbituric acid reactive substances was inhibited by the addition of 4-POBN. The intensity of this inhibitory effect was dependent on the time when 4-POBN was added to the mixture of PAPC-liposomes and Fe2+/AsA solution, and no inhibitory effect could be observed after 4 min. The signal intensity of the carbon-centered radical adduct was dependent on the lipid concentration of PAPC-liposomes. These results suggest that the alkyl radicals generated from PAPC-liposome peroxidation induced by Fe2+/AsA were trapped by DMPO or 4-POBN at an earlier stage of lipid peroxidation. PMID:8799472

  13. Argon protects against hypoxic-ischemic brain injury in neonatal rats through activation of nuclear factor (erythroid-derived 2)-like 2.

    PubMed

    Zhao, Hailin; Mitchell, Sian; Ciechanowicz, Sarah; Savage, Sinead; Wang, Tianlong; Ji, Xunming; Ma, Daqing

    2016-05-01

    Perinatal hypoxic ischaemic encephalopathy (HIE) has a high mortality rate with neuropsychological impairment. This study investigated the neuroprotective effects of argon against neonatal hypoxic-ischaemic brain injury.In vitro cortical neuronal cell cultures derived from rat foetuses were subjected to an oxygen and glucose deprivation (OGD) challenge for 90 minutes and then exposed to 70% argon or nitrogen with 5% carbon dioxide and balanced with oxygen for 2 hours.In vivo, seven-day-old rats were subjected to unilateral common carotid artery ligation followed by hypoxic (8% oxygen balanced with nitrogen) insult for 90 minutes. They were exposed to 70% argon or nitrogen balanced with oxygen for 2 hours. In vitro, argon treatment of cortical neuronal cultures resulted in a significant increase of p-mTOR and Nuclear factor (erythroid-derived 2)-like 2(Nrf2) and protection against OGD challenge. Inhibition of m-TOR through Rapamycin or Nrf2 through siRNA abolished argon-mediated cyto-protection. In vivo, argon exposure significantly enhanced Nrf2 and its down-stream effector NAD(P)H Dehydrogenase, Quinone 1(NQO1) and superoxide dismutase 1(SOD1). Oxidative stress, neuroinflammation and neuronal cell death were significantly decreased and brain infarction was markedly reduced. Blocking PI-3K through wortmannin or ERK1/2 through U0126 attenuated argon-mediated neuroprotection.These data provide a new molecular mechanism for the potential application of Argon as a neuroprotectant in HIE.

  14. Synthesis of Amino- and Nitro-Substituted Heterocycles as Insensitive Energetic Materials

    SciTech Connect

    Pagoria, P F; Lee, G S; Mitchell, A R; Schmidt, R D

    2001-08-23

    In this paper we will describe the synthesis of several amino- and nitro-substituted heterocycles, examples from a continuing research project targeted at the synthesis of new, insensitive energetic materials that possess at least 80% the power of HMX (28% more power than TATB). Recently we reported the synthesis and scale-up of the insensitive energetic material, 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105). The energy content (81% the power of HMX) and thermal stability of LLM-105 make it a viable candidate material for insensitive boosters and deep oil perforation. We will report on recent synthetic improvements and several performance and safety tests performed on LLM-105, including a 1 in. cylinder shot and plate dent. We will also report on the synthesis and characterization of 4-amino-3,5-dinitropyrazole (LLM-116), an interesting new insensitive energetic material with a measured crystal density of 1.90 g/cc, to our knowledge the highest density yet measured for a five-membered heterocycle containing amino- and nitro-substituents. LLM-116 was synthesized by reacting 3,5-dinitropyrazole with 1,1,1-trimethylhydrazinium iodide (TMHI) in DMSO in the presence of base. The synthesis and characterization of 4-amino-5-nitro-1,2,3-triazole (ANTZ) and 43-dinitro-1,2,3-triazole (DNTZ), first described by Baryshnikov and coworkers, will also be presented along with the synthesis of several new energetic materials derived from ANTZ and DNTZ.

  15. High-performance liquid chromatographic determination of linoleic acid peroxide-derived radicals using electrochemical detection.

    PubMed

    Iwahashi, H

    2000-12-29

    High-performance liquid chromatography-electrochemical detection (HPLC-ED) was applied to detect 13-hydroperoxide octadecadienoic acid (13-HPODE)-derived radicals such as the pentyl radical and octanoic acid radical. The 13-HPODE-derived radicals were successfully detected using HPLC-ED by the combined use of the spin-trapping technique with alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone (4-POBN). The 4-POBN-pentyl radical adduct was detected at the retention time of 18.2 +/- 0.3 min on the elution profile of HPLC-ED with an ODS column (15 cm x 4.6 mm I.D.) using a flow-rate of 1.0 ml/min with 50 mM ammonium acetate in 29% (v/v) aqueous acetonitrile. The 4-POBN-octanoic acid radical adduct was also detected at the retention time of 13.7 +/- 0.7 min using a flow-rate of 1.0 ml/min with 50 mM ammonium acetate in 14% (v/v) aqueous acetonitrile. The concentrations of the 4-POBN radical adducts were determined using HPLC-ED without an internal standard. HPLC-ED is 100 times as sensitive as HPLC-electron spin resonance (ESR) under the ESR and ED conditions employed here. Even 1.8 pmol of the 4-POBN-pentyl (or octanoic acid) radical adduct was detectable using PMID:11204234

  16. heterogeneous equilibration between solid and liquid phases in research on the lower oxidation states of the actinide elements

    SciTech Connect

    Mikheev, N.B.; Kamenskaya, A.N.; Konovalova, N.A.; Kulyukhin, S.A.; Rumer, I.A.

    1986-07-01

    Measurements have been made on the cocrystallization of Fe/sup 2 +/ and Md/sup +/ with NaCl and KCl in water-ethanol solutions in the presence of divalent lanthanides. A thermodynamic consideration showed that mendelevium is reduced to the 1+ oxidation state at the Eu/sup 2 +/ potential and cocrystallizes with KCl and NaCl isomorphously. Fermium in the same medium is reduced by Sm/sup 2 +/ only to the 2/sup +/ oxidation state and forms anomalous mixed crystals AMC with KCl, with the cocrystallization coefficient increasing linearly with (Cl/sup -/). These relationships show that Md/sup +/ and Fm/sup 2 +/ do not form stable chloride, complexes, and in that respect they are analogs of the alkali and alkaline-earth elements. The cocrystallization of Md/sup +/ with SmF/sub 2/ and YbF/sub 2/ shows that AMC are formed as when Ag/sup +/ cocrystallizes with SrF/sub 2/.

  17. Electricity generation by anaerobic bacteria and anoxic sediments from hypersaline soda lakes.

    PubMed

    Miller, Laurence G; Oremland, Ronald S

    2008-11-01

    Anaerobic bacteria and anoxic sediments from soda lakes produced electricity in microbial fuel cells (MFCs). No electricity was generated in the absence of bacterial metabolism. Arsenate respiring bacteria isolated from moderately hypersaline Mono Lake (Bacillus selenitireducens), and salt-saturated Searles Lake, CA (strain SLAS-1) oxidized lactate using arsenate as the electron acceptor. However, these cultures grew equally well without added arsenate using the MFC anode as their electron acceptor, and in the process oxidized lactate more efficiently. The decrease in electricity generation by consumption of added alternative electron acceptors (i.e. arsenate) which competed with the anode for available electrons proved to be a useful indicator of microbial activity and hence life in the fuel cells. Shaken sediment slurries from these two lakes also generated electricity, with or without added lactate. Hydrogen added to sediment slurries was consumed but did not stimulate electricity production. Finally, electricity was generated in statically incubated "intact" sediment cores from these lakes. More power was produced in sediment from Mono Lake than from Searles Lake, however microbial fuel cells could detect low levels of metabolism operating under moderate and extreme conditions of salt stress.

  18. Generic dealkylation: a tool for increasing the hit-rate of metabolite rationalization, and automatic customization of mass defect filters.

    PubMed

    Mortishire-Smith, Russell J; Castro-Perez, Jose M; Yu, Kate; Shockcor, John P; Goshawk, Jeff; Hartshorn, Mike J; Hill, Alastair

    2009-04-01

    The use of exact mass liquid chromatography/mass spectrometry (LC/MS) for drug metabolism studies has increased significantly in recent years. Firstly, exact mass measurements facilitate identification of standard biotransformations through the use of narrow window extracted ion chromatograms, which are typically highly selective relative to signals from matrix or dosing components. Secondly, novel metabolites can be characterized via elemental formula calculations and high-resolution product ion spectra. Furthermore, biological background ions can be removed by the use of mass defect filters (MDFs) which filter out ions based on the decimal component of their m/z value. Here, we describe an approach which we term 'generic dealkylation' that in association with other data interpretation tools adds significant value to the assignment process. Generic dealkylation uses a simple strategy to identify those bonds which have the potential to be cleaved by metabolism. In combination with standard phase 1 and phase 2 biotransformations, this allows creation of a chemically intelligent MDF which balances the need to remove matrix background with the requirement of avoiding filtering true metabolites. Secondly, generic dealkylation increases the hit-rate at which non-trivial (i.e. not covered by simple phase 1 oxidations or direct phase 2 conjugations) metabolites can be directly rationalized. The value of the generic dealkylation approach is illustrated by its application to determination of in vitro metabolic routes for two commercial drugs, nefazodone and indinavir.

  19. Myeloperoxidase Inactivates TIMP-1 by Oxidizing Its N-terminal Cysteine Residue

    PubMed Central

    Wang, Yi; Rosen, Henry; Madtes, David K.; Shao, Baohai; Martin, Thomas R.; Heinecke, Jay W.; Fu, Xiaoyun

    2016-01-01

    An imbalance between the proteolytic activity of matrix metalloproteinases (MMPs) and the activity of tissue inhibitors of metalloproteinases (TIMPs) is implicated in tissue injury during inflammation. The N-terminal cysteine of TIMP-1 plays a key role in the inhibitory activity of the protein because it coordinates the essential catalytic Zn2+ of the MMP, preventing the metal ion from functioning. An important mechanism for controlling the interaction of TIMPs with MMPs might involve hypochlorous acid (HOCl), a potent oxidant produced by the myeloperoxidase (MPO) system of phagocytes. Here, we show that HOCl generated by the MPO-H2O2-chloride system inactivates TIMP-1 by oxidizing its N-terminal cysteine. The product is a novel 2-oxo acid. Liquid chromatography-mass spectrometry and tandem mass spectrometry analyses demonstrated that methionine and N-terminal cysteine residues were rapidly oxidized by MPO-derived HOCl but only oxidation of the N-terminal cysteine of TIMP-1 correlated well with loss of inhibitory activity. Importantly, we detected the signature 2-oxo-acid N-terminal peptide in tryptic digests of bronchoalveolar lavage fluid from patients with acute respiratory distress syndrome, demonstrating that TIMP-1 oxidation occurs in vivo. Loss of the N-terminal amino group and disulfide structure are crucial for preventing TIMP-1 from inhibiting MMPs. Our findings suggest that pericellular production of HOCl by phagocytes is a pathogenic mechanism for impairing TIMP-1 activity during inflammation. PMID:17726014

  20. Exploring the Physical, Chemical and Thermal Characteristics of a New Potentially Insensitive High Explosive: RX-55-AE-5

    SciTech Connect

    Weese, R K; Burnham, A K; Turner, H C; Tran, T D

    2006-06-05

    Current work at the Energetic Materials Center, EMC, at Lawrence Livermore National Laboratory (LLNL) includes both understanding properties of old explosives and measuring properties of new ones [1]. The necessity to know and understand the properties of energetic materials is driven by the need to improve performance and enhance stability to various stimuli, such as thermal, friction and impact insult. This review will concentrate on the physical properties of RX-55-AE-5, which is formulated from heterocyclic explosive, 2,6-diamino-3,5-dinitropyrazine-1-oxide, LLM-105, and 2.5% Viton A. Differential scanning calorimetry (DSC) was used to measure a specific heat capacity, C{sub p}, of {approx} 0.950 J/g{center_dot} C and a thermal conductivity, {kappa}, of {approx} 0.475 W/m{center_dot} C. The LLNL kinetics modeling code Kinetics05 and the Advanced Kinetics and Technology Solutions (AKTS) code Thermokinetics were both used to calculate Arrhenius kinetics for decomposition of LLM-105. Both obtained an activation energy barrier E {approx} 180 kJ mol{sup -1} for mass loss in an open pan. Thermal mechanical analysis, TMA, was used to measure the coefficient of thermal expansion (CTE). The CTE for this formulation was calculated to be {approx} 61 {micro}m/m{center_dot} C. Impact, spark, friction are also reported.

  1. Cellulose oxidation and bleaching processes based on recombinant Myriococcum thermophilum cellobiose dehydrogenase.

    PubMed

    Flitsch, Annemarie; Prasetyo, Endry Nugroho; Sygmund, Christoph; Ludwig, Roland; Nyanhongo, Gibson S; Guebitz, Georg M

    2013-01-10

    Myriococcum thermophilum cellobiose dehydrogenase (MtCDH) was expressed in Pichia pastoris using the pPICZαA expression vector under the control of methanol inducible AOX promoter. The purified recombinant MtCDH with a specific activity of 3.1 Umg(-1) was characterized to obtain kinetic constants for various carbohydrate substrates. Additionally, the C1 oxidation of the reducing ends of cellobiose, cellotetraose and maltotriose by MtCDH was verified by HPLC-MS. MtCDH was employed to oxidize several different cellulose-based materials by production of hydrogen peroxide. Based on the obtained results a one-pot enzymatic scouring/bleaching process for cotton fabrics was developed using pectinases as scouring agent and MtCDH to produce H(2)O(2) for bleaching. An average increase in whiteness (Berger) ΔE of 26 and an average 95% increase in wettability were observed in all MtCDH treated fabrics. In addition, MtCDH oxidized typical colored cotton flavonoids (morin, rutin, isoquercitrin). PMID:23199740

  2. Structural and Functional Characterization of a Lytic Polysaccharide Monooxygenase with Broad Substrate Specificity*

    PubMed Central

    Borisova, Anna S.; Isaksen, Trine; Dimarogona, Maria; Kognole, Abhishek A.; Mathiesen, Geir; Várnai, Anikó; Røhr, Åsmund K.; Payne, Christina M.; Sørlie, Morten; Sandgren, Mats; Eijsink, Vincent G. H.

    2015-01-01

    The recently discovered lytic polysaccharide monooxygenases (LPMOs) carry out oxidative cleavage of polysaccharides and are of major importance for efficient processing of biomass. NcLPMO9C from Neurospora crassa acts both on cellulose and on non-cellulose β-glucans, including cellodextrins and xyloglucan. The crystal structure of the catalytic domain of NcLPMO9C revealed an extended, highly polar substrate-binding surface well suited to interact with a variety of sugar substrates. The ability of NcLPMO9C to act on soluble substrates was exploited to study enzyme-substrate interactions. EPR studies demonstrated that the Cu2+ center environment is altered upon substrate binding, whereas isothermal titration calorimetry studies revealed binding affinities in the low micromolar range for polymeric substrates that are due in part to the presence of a carbohydrate-binding module (CBM1). Importantly, the novel structure of NcLPMO9C enabled a comparative study, revealing that the oxidative regioselectivity of LPMO9s (C1, C4, or both) correlates with distinct structural features of the copper coordination sphere. In strictly C1-oxidizing LPMO9s, access to the solvent-facing axial coordination position is restricted by a conserved tyrosine residue, whereas access to this same position seems unrestricted in C4-oxidizing LPMO9s. LPMO9s known to produce a mixture of C1- and C4-oxidized products show an intermediate situation. PMID:26178376

  3. The cytochrome c maturation operon is involved in manganese oxidation in Pseudomonas putida GB-1

    SciTech Connect

    Vrind, J.P.M. de; Brouwers, G.J.; Corstijens, P.L.A.M.; Dulk, J. den; Vrind-de Jong, E.W. de

    1998-10-01

    A Pseudomonas putida strain, strain GB-1, oxidizes Mn{sup 2+} to Mn oxide in the early stationary growth phase. It also secretes a siderophore (identified as pyoverdine) when it is subjected to iron limitation. After transposon (Tn5) mutagenesis several classes of mutants with differences in Mn{sup 2+} oxidation and/or secretion of the Mn{sup 2+}-oxidizing activity were identified. Preliminary analysis of the Tn5 insertion site in one of the nonoxidizing mutants suggested that a multicopper oxidase-related enzyme is involved in Mn{sup 2+} oxidation. The insertion site in another mutant was preliminarily identified as a gene involved in the general protein secretion pathway. Two mutants defective in Mn{sup 2+}-oxidizing activity also secreted porphyrins into the medium and appeared to be derepressed for pyoverdine production. These strains were chosen for detailed analysis. Both mutants were shown to contain Tn5 insertions in the ccmF gene, which is part of the cytochrome c maturation operon. They were cytochrome oxidase negative and did not contain c-type cytochromes. Complementation with part of the ccm operon isolated from the wild type restored the phenotype of the parent strain. These results indicate that a functional ccm operon is required for Mn{sup 2+} oxidation in P. putida GB-1. A possible relationship between porphyrin secretion resulting from the ccm mutation and stimulation of pyoverdine production is discussed.

  4. Catalytic and mechanistic insights of the low-temperature selective oxidation of methane over Cu-promoted Fe-ZSM-5.

    PubMed

    Hammond, Ceri; Jenkins, Robert L; Dimitratos, Nikolaos; Lopez-Sanchez, Jose Antonio; ab Rahim, Mohd Hasbi; Forde, Michael M; Thetford, Adam; Murphy, Damien M; Hagen, Henk; Stangland, Eric E; Moulijn, Jacob M; Taylor, Stuart H; Willock, David J; Hutchings, Graham J

    2012-12-01

    The partial oxidation of methane to methanol presents one of the most challenging targets in catalysis. Although this is the focus of much research, until recently, approaches had proceeded at low catalytic rates (<10 h(-1)), not resulted in a closed catalytic cycle, or were unable to produce methanol with a reasonable selectivity. Recent research has demonstrated, however, that a system composed of an iron- and copper-containing zeolite is able to catalytically convert methane to methanol with turnover frequencies (TOFs) of over 14,000 h(-1) by using H(2)O(2) as terminal oxidant. However, the precise roles of the catalyst and the full mechanistic cycle remain unclear. We hereby report a systematic study of the kinetic parameters and mechanistic features of the process, and present a reaction network consisting of the activation of methane, the formation of an activated hydroperoxy species, and the by-production of hydroxyl radicals. The catalytic system in question results in a low-energy methane activation route, and allows selective C(1)-oxidation to proceed under intrinsically mild reaction conditions. PMID:23150452

  5. Spin-trappers and vitamin E prolong endurance to muscle fatigue in mice

    SciTech Connect

    Novelli, G.P.; Bracciotti, G.; Falsini, S. )

    1990-01-01

    The involvement of free radicals in endurance to muscle effort is suggested by experimental and clinical data. Therefore, experiments have been performed to observe the effect of trapping free radicals on endurance to swimming in mice. Animals were injected intraperitoneally with each of three spin-trappers (N-tert-Butyl-alpha-Phenyl-Nitrone (PBN),alpha-4-Pyridyil-1-Oxide-N-tert-Butyl-Nitrone (POBN) and 5,5-Dimethyl-1-Pirrolyn-N-Oxide (DMPO): 0.2 ml of 10(-1) molar solution). Each mouse was submitted to a swimming test to control resistance to exhaustion (a) without any treatment, (b) after administration of each spin-trapper in a random order (c) after saline. Control experiments were performed with saline and with vitamin E. Endurance to swimming was greatly prolonged by pretreatment with all the spin-trappers (DMPO less than 0.0001; POBN less than 0.0001; PBN less than 0.001) and with Vitamin E. Experiments state that compared to treatment with spin-trappers or Vitamin E, administration of saline alone did not enhance time to exhaustion so that the increase in time to exhaustion with the various free radical scavengers was not the effect of training. Therefore, free radicals could be considered as one of the factors terminating muscle effort in mice.

  6. Electricity generation by anaerobic bacteria and anoxic sediments from hypersaline soda lakes

    USGS Publications Warehouse

    Miller, L.G.; Oremland, R.S.

    2008-01-01

    Anaerobic bacteria and anoxic sediments from soda lakes produced electricity in microbial fuel cells (MFCs). No electricity was generated in the absence of bacterial metabolism. Arsenate respiring bacteria isolated from moderately hypersaline Mono Lake (Bacillus selenitireducens), and salt-saturated Searles Lake, CA (strain SLAS-1) oxidized lactate using arsenate as the electron acceptor. However, these cultures grew equally well without added arsenate using the MFC anode as their electron acceptor, and in the process oxidized lactate more efficiently. The decrease in electricity generation by consumption of added alternative electron acceptors (i.e. arsenate) which competed with the anode for available electrons proved to be a useful indicator of microbial activity and hence life in the fuel cells. Shaken sediment slurries from these two lakes also generated electricity, with or without added lactate. Hydrogen added to sediment slurries was consumed but did not stimulate electricity production. Finally, electricity was generated in statically incubated "intact" sediment cores from these lakes. More power was produced in sediment from Mono Lake than from Searles Lake, however microbial fuel cells could detect low levels of metabolism operating under moderate and extreme conditions of salt stress. ?? 2008 US Government.

  7. Metal-Organic Frameworks (MOFs) of a Cubic Metal Cluster with Multicentered Mn(I)-Mn(I) Bonds.

    PubMed

    Hu, Huan-Cheng; Hu, Han-Shi; Zhao, Bin; Cui, Ping; Cheng, Peng; Li, Jun

    2015-09-28

    MOFs with both multicentered metal-metal bonds and low-oxidation-state (LOS) metal ions have been underexplored hitherto. Here we report the first cubic [Mn(I) 8 ] cluster-based MOF (1) with multicentered Mn(I)-Mn(I) bonds and +1 oxidation state of manganese (Mn(I) or Mn(I)), as is supported by single-crystal structure determination, XPS analyses, and quantum chemical studies. Compound 1 possesses the shortest Mn(I)-Mn(I) bond of 2.372 Å. Theoretical studies with density functional theory (DFT) reveal extensive electron delocalization over the [Mn(I) 8 ] cube. The 48 electrons in the [Mn(I) 8 ] cube fully occupy half of the 3d-based and the lowest 4s-based bonding orbitals, with six electrons lying at the nonbonding 3d-orbitals. This bonding feature renders so-called cubic aromaticity. Magnetic properties measurements show that 1 is an antiferromagnet. This work is expected to inspire further investigation of cubic metal-metal bonding, MOF materials with LOS metals, and metalloaromatic theory.

  8. Effects of exposure to sublethal propiconazole on intestine-related biochemical responses in rainbow trout, Oncorhynchus mykiss.

    PubMed

    Li, Zhi-Hua; Zlabek, Vladimir; Grabic, Roman; Li, Ping; Machova, Jana; Velisek, Josef; Randak, Tomas

    2010-05-14

    The effect of long-term (30 days) exposure to PCZ (0.2, 50, and 500 microg l(-1)) on intestine-related biochemical markers in rainbow trout was investigated. Multiple biomarkers were measured, including digestive enzymes (proteolytic enzymes and amylase), antioxidant responses (TBARS, CP, SOD, CAT, GR and GPx) and energy metabolic parameters (RNA/DNA ratio, Na(+)-K(+)-ATPase). Exposure to 500 microg l(-1) PCZ led to significantly inhibited (p<0.01) proteolytic enzyme and amylase activity. Activities of the antioxidant enzymes SOD, CAT, and GPx gradually increased at lower PCZ concentrations (0.2 and 50 microg l(-1)). At the highest concentration (500 microg l(-1)), oxidative stress was apparent as significant higher (p<0.05) lipid peroxidation and protein carbonyls, associated with an inhibition of antioxidant enzymes activity. Moreover, energy metabolic parameters (RNA/DNA ratio, Na(+)-K(+)-ATPase) were significantly inhibited (p<0.01) in the intestines of fish exposed to 500 microg l(-1) PCZ, compared with controls. We suggest that long-term exposure to PCZ could result in several responses in intestine-related biochemical markers, which potentially could be used as indicators for monitoring residual PCZ present in the aquatic environment.

  9. Interplay between pro-inflammatory cytokines and brain oxidative stress biomarkers: evidence of parallels between butyl paraben intoxication and the valproic acid brain physiopathology in autism rat model.

    PubMed

    Hegazy, Hoda G; Ali, Elham H A; Elgoly, Amany H Mahmoud

    2015-02-01

    Butyl paraben is a preservative used in food, drugs and cosmetics. Neurotoxic effect was reported recently beside the potential estrogenic activity of parabens. There is controversy as to the potential harmful effects of butyl parabens, which are suspected to contribute to autism and learning disabilities. The purpose of this study was to examine the similarities between paraben intoxication signs in the rat brain and brain markers in an autistic like rat model. This study provides evidence of many parallels between the two, including (1) oxidative stress, (2) decreased reduced glutathione levels and elevated oxidised glutathione, (3) mitochondrial dysfunction, and (4) neuroinflammation and increased pro-inflammatory cytokine levels in the brain (tumour necrosis factor-alpha, interleukin-1-beta, and interleukin-6). (5) Increased protein oxidation reported by a significant increase in 3-nitrotyrosine (3-NT)/tyrosine ratio. (6) A marked disturbance was found in the production of energy carriers (AMP, ATP and AMP/ATP ratio) in comparison with the control. The evidence suggests that paraben may, to some extent, either cause or contribute to the brain physiopathology in ASDs or pathogens that produce the brain pathology observed in the diagnosed rat model of ASD.

  10. Epigenetic mechanisms underlying cognitive impairment and Alzheimer disease hallmarks in 5XFAD mice

    PubMed Central

    Griñán-Ferré, Christian; Sarroca, Sara; Ivanova, Aleksandra; Puigoriol-Illamola, Dolors; Aguado, Fernando; Camins, Antoni; Sanfeliu, Coral; Pallàs, Mercè

    2016-01-01

    5XFAD is an early-onset mouse transgenic model of Alzheimer disease (AD). Up to now there are no studies that focus on the epigenetic changes produced as a result of Aβ-42 accumulation and the possible involvement in the different expression of related AD-genes. Under several behavioral and cognition test, we found impairment in memory and psychoemotional changes in female 5XFAD mice in reference to wild type that worsens with age. Cognitive changes correlated with alterations on protein level analysis and gene expression of markers related with tau aberrant phosphorylation, amyloidogenic pathway (APP, BACE1), Oxidative Stress (iNOS, Aldh2) and inflammation (astrogliosis, TNF-α and IL-6); no changes were found in non-amyloidogenic pathway indicators such as ADAM10. Epigenetics changes as higher CpG methylation and transcriptional changes in DNA methyltransferases (DNMTs) family were found. Dnmt1 increases in younger 5XFAD and Dnmt3a and b high levels in the oldest transgenic mice. Similar pattern was found with histone methyltransferases such as Jarid1a and G9a. Histone deacetylase 2 (Hdac2) or Sirt6., both related with cognition and memory, presented a similar pattern. Taken together, these hallmarks presented by the 5XFAD model prompted its use in assessing different potential therapeutic interventions based on epigenetic targets after earlier amyloid deposition. PMID:27013617

  11. Integrating discrete stochastic models and single-cell experiments to infer predictive models of MAPK-induced transcription dynamics

    NASA Astrophysics Data System (ADS)

    Munsky, Brian

    2015-03-01

    MAPK signal-activated transcription plays central roles in myriad biological processes including stress adaptation responses and cell fate decisions. Recent single-cell and single-molecule experiments have advanced our ability to quantify the spatial, temporal, and stochastic fluctuations for such signals and their downstream effects on transcription regulation. This talk explores how integrating such experiments with discrete stochastic computational analyses can yield quantitative and predictive understanding of transcription regulation in both space and time. We use single-molecule mRNA fluorescence in situ hybridization (smFISH) experiments to reveal locations and numbers of multiple endogenous mRNA species in 100,000's of individual cells, at different times and under different genetic and environmental perturbations. We use finite state projection methods to precisely and efficiently compute the full joint probability distributions of these mRNA, which capture measured spatial, temporal and correlative fluctuations. By combining these experimental and computational tools with uncertainty quantification, we systematically compare models of varying complexity and select those which give optimally precise and accurate predictions in new situations. We use these tools to explore two MAPK-activated gene regulation pathways. In yeast adaptation to osmotic shock, we analyze Hog1 kinase activation of transcription for three different genes STL1 (osmotic stress), CTT1 (oxidative stress) and HSP12 (heat shock). In human osteosarcoma cells under serum induction, we analyze ERK activation of c-Fos transcription.

  12. Effect of Dioxygen on Copper(II) Binding to α-Synuclein

    PubMed Central

    Lucas, Heather R.; Lee, Jennifer C.

    2010-01-01

    Using the fluorescent amino acid tryptophan (Trp), we have characterized the copper(II) binding of F4W α-synuclein in the presence and absence of dioxygen at neutral pH. Variations in Trp fluorescence indicate that copper(II) binding is enhanced by the presence of dioxygen, with the apparent dissociation constant (Kd(app)) changing from 100 nM (anaerobic) to 10 nM (aerobic). To investigate the possible role of methionine oxidation, complementary work focused on synthetic peptide models of the N-terminal Cu(II)-α-syn site, MDV(F/W) and M*DV(F/W), where M*= methionine sulfoxide. Furthermore, we employed circular dichroism (CD) spectroscopy to demonstrate that the phenyl-to-indole (F→W) substitution does not alter copper(II) binding properties and to confirm the 1:1 metal-peptide binding stoichiometry. CD comparisons also revealed that Met1 oxidation does not affect the copper-peptide conformation and further suggested the possible existence of a CuII-Trp/Phe (cation-π) interaction. PMID:20064662

  13. Effect of dioxygen on copper(II) binding to alpha-synuclein.

    PubMed

    Lucas, Heather R; Lee, Jennifer C

    2010-03-01

    Using the fluorescent amino acid tryptophan (Trp), we have characterized the copper(II) binding of F4W alpha-synuclein in the presence and absence of dioxygen at neutral pH. Variations in Trp fluorescence indicate that copper(II) binding is enhanced by the presence of dioxygen, with the apparent dissociation constant (K(d(app))) changing from 100nM (anaerobic) to 10nM (aerobic). To investigate the possible role of methionine oxidation, complementary work focused on synthetic peptide models of the N-terminal Cu(II)-alpha-syn site, MDV(F/W) and M( *)DV(F/W), where M( *)=methionine sulfoxide. Furthermore, we employed circular dichroism (CD) spectroscopy to demonstrate that the phenyl-to-indole (F-->W) substitution does not alter copper(II) binding properties and to confirm the 1:1 metal-peptide binding stoichiometry. CD comparisons also revealed that Met1 oxidation does not affect the copper-peptide conformation and further suggested the possible existence of a Cu(II)-Trp/Phe (cation-pi) interaction. PMID:20064662

  14. ESR evidence for in vivo formation of free radicals in tissue of mice exposed to single-walled carbon nanotubes.

    PubMed

    Shvedova, A A; Kisin, E R; Murray, A R; Mouithys-Mickalad, A; Stadler, K; Mason, R P; Kadiiska, M

    2014-08-01

    Nanomaterials are being utilized in an increasing variety of manufactured goods. Because of their unique physicochemical, electrical, mechanical, and thermal properties, single-walled carbon nanotubes (SWCNTs) have found numerous applications in the electronics, aerospace, chemical, polymer, and pharmaceutical industries. Previously, we have reported that pharyngeal exposure of C57BL/6 mice to SWCNTs caused dose-dependent formation of granulomatous bronchial interstitial pneumonia, fibrosis, oxidative stress, acute inflammatory/cytokine responses, and a decrease in pulmonary function. In the current study, we used electron spin resonance (ESR) to directly assess whether exposure to respirable SWCNTs caused formation of free radicals in the lungs and in two distant organs, the heart and liver. Here we report that exposure to partially purified SWCNTs (HiPco technique, Carbon Nanotechnologies, Inc., Houston, TX, USA) resulted in the augmentation of oxidative stress as evidenced by ESR detection of α-(4-pyridyl-1-oxide)-N-tert-butylnitrone spin-trapped carbon-centered lipid-derived radicals recorded shortly after the treatment. This was accompanied by a significant depletion of antioxidants and elevated biomarkers of inflammation presented by recruitment of inflammatory cells and an increase in proinflammatory cytokines in the lungs, as well as development of multifocal granulomatous pneumonia, interstitial fibrosis, and suppressed pulmonary function. Moreover, pulmonary exposure to SWCNTs also caused the formation of carbon-centered lipid-derived radicals in the heart and liver at later time points (day 7 postexposure). Additionally, SWCNTs induced a significant accumulation of oxidatively modified proteins, increase in lipid peroxidation products, depletion of antioxidants, and inflammatory response in both the heart and the liver. Furthermore, the iron chelator deferoxamine noticeably reduced lung inflammation and oxidative stress, indicating an important role for

  15. Patterns of ecological specialization among microbial populations in the Red Sea and diverse oligotrophic marine environments.

    PubMed

    Thompson, Luke R; Field, Chris; Romanuk, Tamara; Ngugi, David; Siam, Rania; El Dorry, Hamza; Stingl, Ulrich

    2013-06-01

    Large swaths of the nutrient-poor surface ocean are dominated numerically by cyanobacteria (Prochlorococcus), cyanobacterial viruses (cyanophage), and alphaproteobacteria (SAR11). How these groups thrive in the diverse physicochemical environments of different oceanic regions remains poorly understood. Comparative metagenomics can reveal adaptive responses linked to ecosystem-specific selective pressures. The Red Sea is well-suited for studying adaptation of pelagic-microbes, with salinities, temperatures, and light levels at the extreme end for the surface ocean, and low nutrient concentrations, yet no metagenomic studies have been done there. The Red Sea (high salinity, high light, low N and P) compares favorably with the Mediterranean Sea (high salinity, low P), Sargasso Sea (low P), and North Pacific Subtropical Gyre (high light, low N). We quantified the relative abundance of genetic functions among Prochlorococcus, cyanophage, and SAR11 from these four regions. Gene frequencies indicate selection for phosphorus acquisition (Mediterranean/Sargasso), DNA repair and high-light responses (Red Sea/Pacific Prochlorococcus), and osmolyte C1 oxidation (Red Sea/Mediterranean SAR11). The unexpected connection between salinity-dependent osmolyte production and SAR11 C1 metabolism represents a potentially major coevolutionary adaptation and biogeochemical flux. Among Prochlorococcus and cyanophage, genes enriched in specific environments had ecotype distributions similar to nonenriched genes, suggesting that inter-ecotype gene transfer is not a major source of environment-specific adaptation. Clustering of metagenomes using gene frequencies shows similarities in populations (Red Sea with Pacific, Mediterranean with Sargasso) that belie their geographic distances. Taken together, the genetic functions enriched in specific environments indicate competitive strategies for maintaining carrying capacity in the face of physical stressors and low nutrient availability.

  16. Regulation of Reactive Oxygen Species and the Antioxidant Protein DJ-1 in Mastocytosis.

    PubMed

    Kim, Do-Kyun; Beaven, Michael A; Kulinski, Joseph M; Desai, Avanti; Bandara, Geethani; Bai, Yun; Prussin, Calman; Schwartz, Lawrence B; Komarow, Hirsh; Metcalfe, Dean D; Olivera, Ana

    2016-01-01

    Neoplastic accumulation of mast cells in systemic mastocytosis (SM) associates with activating mutations in the receptor tyrosine kinase KIT. Constitutive activation of tyrosine kinase oncogenes has been linked to imbalances in oxidant/antioxidant mechanisms in other myeloproliferative disorders. However, the impact of KIT mutations on the redox status in SM and the potential therapeutic implications are not well understood. Here, we examined the regulation of reactive oxygen species (ROS) and of the antioxidant protein DJ-1 (PARK-7), which increases with cancer progression and acts to lessen oxidative damage to malignant cells, in relationship with SM severity. ROS levels were increased in both indolent (ISM) and aggressive variants of the disease (ASM). However, while DJ-1 levels were reduced in ISM with lower mast cell burden, they rose in ISM with higher mast cell burden and were significantly elevated in patients with ASM. Studies on mast cell lines revealed that activating KIT mutations induced constant ROS production and consequent DJ-1 oxidation and degradation that could explain the reduced levels of DJ-1 in the ISM population, while IL-6, a cytokine that increases with disease severity, caused a counteracting transcriptional induction of DJ-1 which would protect malignant mast cells from oxidative damage. A mouse model of mastocytosis recapitulated the biphasic changes in DJ-1 and the escalating IL-6, ROS and DJ-1 levels as mast cells accumulate, findings which were reversed with anti-IL-6 receptor blocking antibody. Our findings provide evidence of increased ROS and a biphasic regulation of the antioxidant DJ-1 in variants of SM and implicate IL-6 in DJ-1 induction and expansion of mast cells with KIT mutations. We propose consideration of IL-6 blockade as a potential adjunctive therapy in the treatment of patients with advanced mastocytosis, as it would reduce DJ-1 levels making mutation-positive mast cells vulnerable to oxidative damage. PMID:27611333

  17. Altered protein S-glutathionylation identifies a potential mechanism of resistance to acetaminophen-induced hepatotoxicity.

    PubMed

    McGarry, David J; Chakravarty, Probir; Wolf, C Roland; Henderson, Colin J

    2015-11-01

    Acetaminophen (APAP) is the most commonly used over-the-counter analgesic. However, hepatotoxicity induced by APAP is a major clinical issue, and the factors that define sensitivity to APAP remain unclear. We have previously demonstrated that mice nulled for glutathione S-transferase Pi (GSTP) are resistant to APAP-induced hepatotoxicity. This study aims to exploit this difference to delineate pathways of importance in APAP toxicity. We used mice nulled for GSTP and heme oxygenase-1 oxidative stress reporter mice, together with a novel nanoflow liquid chromatography-tandem mass spectrometry methodology to investigate the role of oxidative stress, cell signaling, and protein S-glutathionylation in APAP hepatotoxicity. We provide evidence that the sensitivity difference between wild-type and Gstp1/2(-/-) mice is unrelated to the ability of APAP to induce oxidative stress, despite observing significant increases in c-Jun N-terminal kinase and extracellular signal-regulated kinase phosphorylation in wild-type mice. The major difference in response to APAP was in the levels of protein S-glutathionylation: Gstp1/2(-/-) mice exhibited a significant increase in the number of S-glutathionylated proteins compared with wild-type animals. Remarkably, these S-glutathionylated proteins are involved in oxidative phosphorylation, respiratory complexes, drug metabolism, and mitochondrial apoptosis. Furthermore, we found that S-glutathionylation of the rate-limiting glutathione-synthesizing enzyme, glutamate cysteine ligase, was markedly increased in Gstp1/2(-/-) mice in response to APAP. The data demonstrate that S-glutathionylation provides an adaptive response to APAP and, as a consequence, suggest that this is an important determinant in APAP hepatotoxicity. This work identifies potential novel avenues associated with cell survival for the treatment of chemical-induced hepatotoxicity. PMID:26311813

  18. Direct evidence of iNOS-mediated in vivo free radical production and protein oxidation in acetone-induced ketosis.

    PubMed

    Stadler, Krisztian; Bonini, Marcelo G; Dallas, Shannon; Duma, Danielle; Mason, Ronald P; Kadiiska, Maria B

    2008-08-01

    Diabetic patients frequently encounter ketosis that is characterized by the breakdown of lipids with the consequent accumulation of ketone bodies. Several studies have demonstrated that reactive species are likely to induce tissue damage in diabetes, but the role of the ketone bodies in the process has not been fully investigated. In this study, electron paramagnetic resonance (EPR) spectroscopy combined with novel spin-trapping and immunological techniques has been used to investigate in vivo free radical formation in a murine model of acetone-induced ketosis. A six-line EPR spectrum consistent with the alpha-(4-pyridyl-1-oxide)-N-t-butylnitrone radical adduct of a carbon-centered lipid-derived radical was detected in the liver extracts. To investigate the possible enzymatic source of these radicals, inducible nitric oxide synthase (iNOS) and NADPH oxidase knockout mice were used. Free radical production was unchanged in the NADPH oxidase knockout but much decreased in the iNOS knockout mice, suggesting a role for iNOS in free radical production. Longer-term exposure to acetone revealed iNOS overexpression in the liver together with protein radical formation, which was detected by confocal microscopy and a novel immunospin-trapping method. Immunohistochemical analysis revealed enhanced lipid peroxidation and protein oxidation as a consequence of persistent free radical generation after 21 days of acetone treatment in control and NADPH oxidase knockout but not in iNOS knockout mice. Taken together, our data demonstrate that acetone administration, a model of ketosis, can lead to protein oxidation and lipid peroxidation through a free radical-dependent mechanism driven mainly by iNOS overexpression.

  19. Thermodynamic basis for redox regulation of the Yap1 signal transduction pathway.

    PubMed

    Mason, Jeremy T; Kim, Sung-Kun; Knaff, David B; Wood, Matthew J

    2006-11-14

    The Yap1 oxidative stress signal transduction pathway found in Saccharomyces cerevisiae is redox-regulated. We have examined the thermodynamic basis of the disulfide/dithiol couples that are involved in the regulation of this pathway. The oxidized form of the Yap1 redox domain (Yap1-RD) fragment, derived from the Yap1 transcription factor, contains two disulfide bonds, one between Cys303 and Cys598 and one between Cys310 and Cys629. Oxidation-reduction titrations reveal the presence of two separate two-electron redox couples in Yap1-RD, with redox midpoint potentials (E(m)) of -155 and -330 mV, respectively, at pH 7.0. We measured E(m) values of -275 and -265 mV for the two cytoplasmic S. cerevisiae thioredoxins, Trx1 and Trx2, respectively, both at pH 7.0. Last, we measured an E(m) value of -255 mV for the Cys36-Cys82 disulfide bond at pH 6.0 in the glutathione peroxidase-like enzyme, oxidant receptor protein (Orp1). We were unable to obtain satisfactory redox titration data for Orp1 at pH 7.0, but if the redox-active disulfide of Orp1 exhibits the -59 mV per pH unit dependence for E(m) typical of protein disulfides in this pH region, an E(m) value of -315 mV can be estimated for Orp1 at pH 7.0 by extrapolation. Together, these data suggest that, at physiological ratios of Trx(ox)/Trx(red), the reduction of both the E(m) = -315 mV disulfide of Orp1 and the E(m) = -330 mV disulfide of Yap1 by either Trx1 or Trx2 would be thermodynamically possible. PMID:17087494

  20. Structural properties and application in lithium cells of Li(Ni0.5Co0.5)1-yFeyO2 (0 ≤ y ≤ 0.25) prepared by sol-gel route: Doping optimization

    NASA Astrophysics Data System (ADS)

    Abdel-Ghany, A. E.; Hashem, A. M.; Elzahany, E. A.; Abuzeid, H. A.; Indris, S.; Nikolowski, K.; Ehrenberg, H.; Zaghib, K.; Mauger, A.; Julien, C. M.

    2016-07-01

    Layered Li(Co0.5Ni0.5)1-yFeyO2 (0.0 ≤ y ≤ 0.25) oxides were prepared by citric-acid assisted sol-gel method. Elemental and structural properties were investigated by energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Raman scattering (RS) and Mössbauer spectroscopy, and magnetometry. EDX images show a homogeneous distribution of Fe ions. XRD and RS spectroscopy reveal that the materials crystallize as a LiNiO2sbnd LiCoO2sbnd LiFeO2 solid solution with the typical rhombohedral α-NaFeO2 structure (R 3 bar m S.G.) up to y = 0.2 at which composition a secondary phase was observed. For y > 0.2 the XRD results show the appearance of the α-LiFeO2 phase with the cubic structure (Fm3m S.G.). The degree of cation mixing investigated by XRD analysis and magnetic measurements is z < 0.04, for y < 0.2. Electrochemical tests of Li(Co0.5Ni0.5)1-yFeyO2 (0.0 ≤ y ≤ 0.1) oxides in lithium cells show the influence of iron substitution. The best results have been obtained for the composition y(Fe) = 0.05, where the electrical conductivity is maximum. A specific capacity 32 mAh g-1 is maintained at 8C rate.

  1. Development of a voltammetric assay, using screen-printed electrodes, for clonazepam and its application to beverage and serum samples.

    PubMed

    Honeychurch, Kevin C; Brooks, Joshua; Hart, John P

    2016-01-15

    This paper describes the development of an electrochemical assay based on screen-printed carbon sensors for the determination of clonazepam in serum and in wine. The cyclic voltammetric behaviour of the drug was investigated and the effects of pH and scan rate on the peak current and peak potential determined. Two reduction peaks were recorded on the initial negative going scan, which were considered to result from the 2e(-), 2 H(+) reduction of the 4,5-azomethine and from the 4e(-), 4 H(+) reduction of the 7-NO2 to a hydroxylamine. On the return positive going scan an oxidation peak was seen, which was considered to result from the 2e(-), 2 H(+) oxidation (O1) of the hydroxylamine to the corresponding nitroso species. At pH 11 the solution of clonazepam was found to turn from clear to yellow in colour and the voltammetric signal of the O1 oxidation process was found to be adsorptive in nature, this was exploited in the development of an adsorptive stripping voltammetric assay. Experimental conditions were then optimised for the differential pulse adsorptive voltammetric measurement of clonazepam in wine and serum samples. It was shown that these analyses could be performed on only 100µL of sample which was deposited on the sensor surface. Mean recoveries of 79.53% (%CV=9.88%) and 88.22% (%CV=14.1%) were calculated for wine fortified with 3.16µg/mL and serum fortified with 12.6µg/mL. PMID:26592640

  2. EPR studies of in vivo radical production by 3,3',5,5'-tetrabromobisphenol A (TBBPA) in the Sprague-Dawley rat

    SciTech Connect

    Chignell, C.F.; Mouithys-Mickalad, A.; Sik, R.H.; Stadler, K.; Kadiiska, M.B.

    2008-07-01

    Brominated flame retardants (BFRs) are present in many consumer products ranging from fabrics to plastics and electronics. Wide use of flame retardants can pose an environmental hazard and it is of interest to determine the mechanism of their toxicity. Of all the BFRs, 3,3',5,5'-tetrabromobisphenol A (TBBPA) is produced in the largest volume. Previous studies by Szymanska et al. (2000) have shown that TBBPA is hepatotoxic in rats. We report here that when TBBPA (100 or 600 mg/kg) dissolved in DMSO and {alpha}-(4-pyridyl-1-oxide)-N-t-butylnitrone (POBN) was administered ip to male Sprague-Dawley rats the POBN/{center_dot}CH{sub 3} spin adduct was detected by electron paramagnetic resonance (EPR) in the bile. When {sup 13}C-DMSO was employed the POBN/{center_dot}C{sup 13}H{sub 3} adduct was observed. Also present in the bile was the 2,6-dibromobenzosemiquinone radical derived from 2,6-dibromohydroquinone, a known metabolite of TBBPA. Reaction of the 2,6-dibromobenzosemiquinone radical with oxygen would generate superoxide from which hydrogen peroxide can form by dismutation. The hydroxyl radical generated via the Fenton reaction from hydrogen peroxide reacts in vivo with DMSO to give the methyl radical which is trapped by POBN. These observations suggest that the hepatotoxicity of TBBPA in rats may be due to the in vivo generation of the hydroxyl radical as a result of redox reactions involving the TBBPA metabolite 2,6-dibromohydroquinone and its corresponding semiquinone radical.

  3. Identification of Tazarotenic Acid as the First Xenobiotic Substrate of Human Retinoic Acid Hydroxylase CYP26A1 and CYP26B1.

    PubMed

    Foti, Robert S; Isoherranen, Nina; Zelter, Alex; Dickmann, Leslie J; Buttrick, Brian R; Diaz, Philippe; Douguet, Dominique

    2016-05-01

    Cytochrome P450 (CYP) 26A1 and 26B1 are heme-containing enzymes responsible for metabolizing all-trans retinoic acid (at-RA). No crystal structures have been solved, and therefore homology models that provide structural information are extremely valuable for the development of inhibitors of cytochrome P450 family 26 (CYP26). The objectives of this study were to use homology models of CYP26A1 and CYP26B1 to characterize substrate binding characteristics, to compare structural aspects of their active sites, and to support the role of CYP26 in the metabolism of xenobiotics. Each model was verified by dockingat-RA in the active site and comparing the results to known metabolic profiles ofat-RA. The models were then used to predict the metabolic sites of tazarotenic acid with results verified by in vitro metabolite identification experiments. The CYP26A1 and CYP26B1 homology models predicted that the benzothiopyranyl moiety of tazarotenic acid would be oriented toward the heme of each enzyme and suggested that tazarotenic acid would be a substrate of CYP26A1 and CYP26B1. Metabolite identification experiments indicated that CYP26A1 and CYP26B1 oxidatively metabolized tazarotenic acid on the predicted moiety, with in vitro rates of metabolite formation by CYP26A1 and CYP26B1 being the highest across a panel of enzymes. Molecular analysis of the active sites estimated the active-site volumes of CYP26A1 and CYP26B1 to be 918 Å(3)and 977 Å(3), respectively. Overall, the homology models presented herein describe the enzyme characteristics leading to the metabolism of tazarotenic acid by CYP26A1 and CYP26B1 and support a potential role for the CYP26 enzymes in the metabolism of xenobiotics. PMID:26937021

  4. Transgenesis of humanized fat1 promotes n-3 polyunsaturated fatty acid synthesis and expression of genes involved in lipid metabolism in goat cells.

    PubMed

    Fan, Yixuan; Ren, Caifang; Wang, Zhibo; Jia, Ruoxin; Wang, Dan; Zhang, Yanli; Zhang, Guomin; Wan, Yongjie; Huang, Mingrui; Wang, Feng

    2016-01-15

    The n-3 fatty acid desaturase gene fat1 codes for the n-3 desaturase enzyme, which can convert n-6 polyunsaturated fatty acids (PUFAs) to n-3 PUFAs. The n-3 PUFAs are essential components required for normal cellular function and have preventive and therapeutic effects on many diseases. Goat is an important domestic animal for human consumption of meat and milk. To elevate the concentrations of n-3 PUFAs and examine the regulatory mechanism of fat1 in PUFA metabolism in goat cells, we successfully constructed a humanized fat1 expression vector and confirmed the efficient expression of fat1 in goat ear skin-derived fibroblast cells (GEFCs) by qRT-PCR and Western blot analysis. Fatty acid analysis showed that fat1 overexpression significantly increased the levels of total n-3 PUFAs and decreased the levels of total n-6 PUFAs in GEFCs. In addition, qRT-PCR results indicate that the FADS1 and FADS2 desaturase genes, ELOV2 and ELOV5 elongase genes, ACO and CPT1 oxidation genes, and PPARa and PPARγ transcription factors are up-regulated, and transcription factors of SREBP-1c gene are down-regulated in the fat1 transgenic goat cells. Overall, fat1-overexpression resulted in an increase in the n-3 fatty acids and altered expression of PUFA synthesis related genes in GEFCs. This work lays a foundation for both the production of fat1 transgenic goats and further study of the mechanism of fat1 function in the PUFAs metabolism. PMID:26474750

  5. Spectroscopy investigation of nanostructured nickel–zinc ferrite obtained by mechanochemical synthesis

    SciTech Connect

    Lazarević, Zorica Ž.; Milutinović, Aleksandra N.; Jovalekić, Čedomir D.; Ivanovski, Valentin N.; Daneu, Nina; Mađarević, Ivan; Romčević, Nebojša Ž.

    2015-03-15

    Highlights: • Nano powder of Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} prepared by a soft mechanochemicaly after 10 h milling. • Phase formation controlled by XRD, Raman and IR spectroscopy. • Spectroscopy measurements indicate that the prepared samples have spinel structure. • The average particles size are found to be around 20 nm. • The degree of inversion is δ = 0.36 for NZF obtained from hydroxides for 10 h. - Abstract: Nano crystalline samples of nickel–zinc ferrite, Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} were prepared by mechanochemical route in a planetary ball mill starting from two mixtures of the appropriate quantities of the powders: case (1) oxide powders: NiO, ZnO and α-Fe{sub 2}O{sub 3} in one case, and in the second case (2) hydroxide powders: Ni(OH){sub 2}, Zn(OH){sub 2} and Fe(OH){sub 3}. In order to monitor the progress of chemical reaction and confirm phase formation, powder samples obtained after 5 h and 10 h of milling were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman, IR and Mössbauer spectroscopy. It is shown that the soft mechanochemical method, i.e. mechanochemical activation of hydroxides, produces high quality single phase Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} samples in much more efficient way. From the IR spectroscopy of single phase samples it is obvious that energy of modes depends on the ratio of cations. The deconvolution of Raman spectra allows to separate contributions of different cations to a particular type of vibration and to estimate the degree of inversion.

  6. Effects of dietary selenium on tissue concentrations, pathology, oxidative stress, and immune function in common eiders (Somateria mollissima).

    PubMed

    Franson, J Christian; Hoffman, David J; Wells-Berlin, Alicia; Perry, Matthew C; Shearn-Bochsler, Valerie; Finley, Daniel L; Flint, Paul L; Hollmén, Tuula

    2007-05-15

    Common eiders (Somateria mollissima) were fed added Se (as L-selenomethionine) in concentrations increasing from 10 to 80 ppm in a pilot study (Study 1) or 20 (low exposure) and up to 60 (high exposure) ppm Se in Study 2. Body weights of Study 1 ducks and high-exposure ducks in Study 2 declined rapidly. Mean concentrations of Se in blood reached 32.4 ppm wet weight in Study 1 and 17.5 ppm wet weight in high-exposure birds in Study 2. Mean Se concentrations in liver ranged from 351 (low exposure, Study 2) to 1252 ppm dry weight (Study 1). Oxidative stress was evidenced by Se-associated effects on glutathione metabolism. As Se concentrations in liver increased, Se-dependent glutathione peroxidase activity, glutathione reductase activity, oxidized glutathione levels, and the ratio of hepatic oxidized to reduced glutathione increased. In Study 2, the T-cell-mediated immune response was adversely affected in high-exposure eiders, but ducks in the low-exposure group exhibited evidence of an enhanced antibody-mediated immune response. Gross lesions in high-exposure ducks included emaciation, absence of thymus, and loss of nails from digits. Histologic lesions included severe depletion of lymphoid organs, hepatopathy, and necrosis of feather pulp and feather epithelium. Field studies showed that apparently healthy sea ducks generally have higher levels of Se in liver than healthy fresh-water birds, but lower than concentrations found in our study. Data indicate that common eiders and probably other sea ducks possess a higher threshold, or adverse effect level, for Se in tissues than fresh-water species. However, common eiders developed signs of Se toxicity similar to those seen in fresh-water birds. PMID:17454562

  7. Interaction between glutamate dehydrogenase (GDH) and L-leucine catabolic enzymes: intersecting metabolic pathways.

    PubMed

    Hutson, Susan M; Islam, Mohammad Mainul; Zaganas, Ioannis

    2011-09-01

    Branched-chain amino acids (BCAAs) catabolism follows sequential reactions and their metabolites intersect with other metabolic pathways. The initial enzymes in BCAA metabolism, the mitochondrial branched-chain aminotransferase (BCATm), which deaminates the BCAAs to branched-chain α-keto acids (BCKAs); and the branched-chain α-keto acid dehydrogenase enzyme complex (BCKDC), which oxidatively decarboxylates the BCKAs, are organized in a supramolecular complex termed metabolon. Glutamate dehydrogenase (GDH1) is found in the metabolon in rat tissues. Bovine GDH1 binds to the pyridoxamine 5'-phosphate (PMP)-form of human BCATm (PMP-BCATm) but not to pyridoxal 5'-phosphate (PLP)-BCATm in vitro. This protein interaction facilitates reamination of the α-ketoglutarate (αKG) product of the GDH1 oxidative deamination reaction. Human GDH1 appears to act like bovine GDH1 but human GDH2 does not show the same enhancement of BCKDC enzyme activities. Another metabolic enzyme is also found in the metabolon is pyruvate carboxylase (PC). Kinetic results suggest that PC binds to the E1 decarboxylase of BCKDC but does not effect BCAA catabolism. The protein interaction of BCATm and GDH1 promotes regeneration of PLP-BCATm which then binds to BCKDC resulting in channeling of the BCKA products from BCATm first half reaction to E1 and promoting BCAA oxidation and net nitrogen transfer from BCAAs. The cycling of nitrogen through glutamate via the actions of BCATm and GDH1 releases free ammonia. Formation of ammonia may be important for astrocyte glutamine synthesis in the central nervous system. In peripheral tissue association of BCATm and GDH1 would promote BCAA oxidation at physiologically relevant BCAA concentrations. PMID:21621574

  8. Linkage of cold acclimation and disease resistance through plant-pathogen interaction pathway in Vitis amurensis grapevine.

    PubMed

    Wu, Jiao; Zhang, Yali; Yin, Ling; Qu, Junjie; Lu, Jiang

    2014-12-01

    Low temperatures cause severe damage to none cold hardy grapevines. A preliminary survey with Solexa sequencing technology was used to analyze gene expression profiles of cold hardy Vitis amurensis 'Zuoshan-1' after cold acclimation at 4 °C for 48 h. A total of 16,750 and 18,068 putative genes were annotated for 4 °C-treated and control library, respectively. Among them, 393 genes were upregulated for at least 20-fold, while 69 genes were downregulated for at least 20-fold under the 4 °C treatment for 48 h. A subset of 101 genes from this survey was investigated further using reverse transcription polymerase chain reaction (RT-PCR). Genes associated with signaling events in pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI), including generation of calcium signals (CNGC, CMLs), jasmonic acid signal (JAZ1), oxidative burst (Rboh), and phosphorylation (FLS2, BAK, MEKK1, MKKs) cascades, were upregulated after cold acclimation. Disease resistance genes (RPM1, RPS5, RIN4, PBS1) in the process of effector-triggered immunity (ETI) were also upregulated in the current condition. Defense-related genes (WRKYs, PR1, MIN7) involved in both PTI and ETI processes were abundantly expressed after cold acclimation. Our results indicated that plant-pathogen interaction pathways were linked to the cold acclimation in V. amurensis grapevine. Other biotic- and abiotic-related genes, such as defense (protein phosphatase 2C, U-box domain proteins, NCED1, stilbene synthase), transcription (DREBs, MYBs, ERFs, ZFPs), signal transduction (kinase, calcium, and auxin signaling), transport (ATP-binding cassette (ABC) transporters, auxin:hydrogen symporter), and various metabolism, were also abundantly expressed in the cold acclimation of V. Amurensis 'Zuoshan-1' grapevine. This study revealed a series of critical genes and pathways to delineate important biological processes affected by low temperature in 'Zuoshan-1'.

  9. Expression and characterization of CYP52 genes involved in the biosynthesis of sophorolipid and alkane metabolism from Starmerella bombicola.

    PubMed

    Huang, Fong-Chin; Peter, Alyssa; Schwab, Wilfried

    2014-01-01

    Three cytochrome P450 monooxygenase CYP52 gene family members were isolated from the sophorolipid-producing yeast Starmerella bombicola (former Candida bombicola), namely, CYP52E3, CYP52M1, and CYP52N1, and their open reading frames were cloned into the pYES2 vector for expression in Saccharomyces cerevisiae. The functions of the recombinant proteins were analyzed with a variety of alkane and fatty acid substrates using microsome proteins or a whole-cell system. CYP52M1 was found to oxidize C16 to C20 fatty acids preferentially. It converted oleic acid (C18:1) more efficiently than stearic acid (C18:0) and linoleic acid (C18:2) and much more effectively than α-linolenic acid (C18:3). No products were detected when C10 to C12 fatty acids were used as the substrates. Moreover, CYP52M1 hydroxylated fatty acids at their ω- and ω-1 positions. CYP52N1 oxidized C14 to C20 saturated and unsaturated fatty acids and preferentially oxidized palmitic acid, oleic acid, and linoleic acid. It only catalyzed ω-hydroxylation of fatty acids. Minor ω-hydroxylation activity against myristic acid, palmitic acid, palmitoleic acid, and oleic acid was shown for CYP52E3. Furthermore, the three P450s were coassayed with glucosyltransferase UGTA1. UGTA1 glycosylated all hydroxyl fatty acids generated by CYP52E3, CYP52M1, and CYP52N1. The transformation efficiency of fatty acids into glucolipids by CYP52M1/UGTA1 was much higher than those by CYP52N1/UGTA1 and CYP52E3/UGTA1. Taken together, CYP52M1 is demonstrated to be involved in the biosynthesis of sophorolipid, whereas CYP52E3 and CYP52N1 might be involved in alkane metabolism in S. bombicola but downstream of the initial oxidation steps.

  10. Augmentation of oxidant injury to human pulmonary epithelial cells by the Pseudomonas aeruginosa siderophore pyochelin.

    PubMed Central

    Britigan, B E; Rasmussen, G T; Cox, C D

    1997-01-01

    Pseudomonas aeruginosa causes acute and chronic infections of the human lung, with resultant tissue injury. We have previously shown that iron bound to pyochelin, a siderophore secreted by the organism to acquire iron, is an efficient catalyst for hydroxyl radical (HO.) formation and augments injury to pulmonary artery endothelial cells resulting from their exposure to superoxide (O2.) and/or H2O2. Sources for O2-. and H2O2 included phorbol myristate acetate (PMA)-stimulated neutrophils and pyocyanin. Pyocyanin, another P. aeruginosa secretory product, undergoes cell-mediated redox, thereby forming O2-. and H2O2. In P. aeruginosa lung infections, damage to airway epithelial cells is probably more extensive than that to endothelial cells. Therefore, we examined whether ferripyochelin also augments oxidant-mediated damage to airway epithelial cells. A549 cells, a human type II alveolar epithelial cell line, was exposed to H2O2, PMA-stimulated neutrophils, or pyocyanin, and injury was determined by release of 51Cr from prelabeled cells. Ferripyochelin significantly increased (> 10-fold) oxidant-mediated cell injury regardless of whether H2O2, neutrophils, or pyocyanin was employed. Apo-pyochelin was not effective, and ferripyochelin was not toxic by itself at the concentrations employed. Spin trapping with alpha-(4-pyrridyl-1-oxide)-N-t-butyl-nitrone-ethanol confirmed the generation of HO., and injury was decreased by a variety of antioxidants, including superoxide dismutase, catalase, and dimethylthiourea. These data are consistent with the hypothesis that the presence of ferripyochelin at sites of P. aeruginosa lung infection could contribute to tissue injury through its ability to promote HO.-mediated damage to airway epithelial cells. PMID:9038317

  11. Diesterified nitrone rescues nitroso-redox levels and increases myocyte contraction via increased SR Ca(2+) handling.

    PubMed

    Traynham, Christopher J; Roof, Steve R; Wang, Honglan; Prosak, Robert A; Tang, Lifei; Viatchenko-Karpinski, Serge; Ho, Hsiang-Ting; Racoma, Ira O; Catalano, Dominic J; Huang, Xin; Han, Yongbin; Kim, Shang-U; Gyorke, Sandor; Billman, George E; Villamena, Frederick A; Ziolo, Mark T

    2012-01-01

    Nitric oxide (NO) and superoxide (O(2) (-)) are important cardiac signaling molecules that regulate myocyte contraction. For appropriate regulation, NO and O(2) (.-) must exist at defined levels. Unfortunately, the NO and O(2) (.-) levels are altered in many cardiomyopathies (heart failure, ischemia, hypertrophy, etc.) leading to contractile dysfunction and adverse remodeling. Hence, rescuing the nitroso-redox levels is a potential therapeutic strategy. Nitrone spin traps have been shown to scavenge O(2) (.-) while releasing NO as a reaction byproduct; and we synthesized a novel, cell permeable nitrone, 2-2-3,4-dihydro-2H-pyrrole 1-oxide (EMEPO). We hypothesized that EMEPO would improve contractile function in myocytes with altered nitroso-redox levels. Ventricular myocytes were isolated from wildtype (C57Bl/6) and NOS1 knockout (NOS1(-/-)) mice, a known model of NO/O(2) (.-) imbalance, and incubated with EMEPO. EMEPO significantly reduced O(2) (.-) (lucigenin-enhanced chemiluminescence) and elevated NO (DAF-FM diacetate) levels in NOS1(-/-) myocytes. Furthermore, EMEPO increased NOS1(-/-) myocyte basal contraction (Ca(2+) transients, Fluo-4AM; shortening, video-edge detection), the force-frequency response and the contractile response to β-adrenergic stimulation. EMEPO had no effect in wildtype myocytes. EMEPO also increased ryanodine receptor activity (sarcoplasmic reticulum Ca(2+) leak/load relationship) and phospholamban Serine16 phosphorylation (Western blot). We also repeated our functional experiments in a canine post-myocardial infarction model and observed similar results to those seen in NOS1(-/-) myocytes. In conclusion, EMEPO improved contractile function in myocytes experiencing an imbalance of their nitroso-redox levels. The concurrent restoration of NO and O(2) (.-) levels may have therapeutic potential in the treatment of various cardiomyopathies. PMID:23300588

  12. Targeting of insect epicuticular lipids by the entomopathogenic fungus Beauveria bassiana: hydrocarbon oxidation within the context of a host-pathogen interaction

    PubMed Central

    Pedrini, Nicolás; Ortiz-Urquiza, Almudena; Huarte-Bonnet, Carla; Zhang, Shizhu; Keyhani, Nemat O.

    2013-01-01

    Broad host range entomopathogenic fungi such as Beauveria bassiana attack insect hosts via attachment to cuticular substrata and the production of enzymes for the degradation and penetration of insect cuticle. The outermost epicuticular layer consists of a complex mixture of non-polar lipids including hydrocarbons, fatty acids, and wax esters. Long chain hydrocarbons are major components of the outer waxy layer of diverse insect species, where they serve to protect against desiccation and microbial parasites, and as recognition molecules or as a platform for semiochemicals. Insect pathogenic fungi have evolved mechanisms for overcoming this barrier, likely with sets of lipid degrading enzymes with overlapping substrate specificities. Alkanes and fatty acids are substrates for a specific subset of fungal cytochrome P450 monooxygenases involved in insect hydrocarbon degradation. These enzymes activate alkanes by terminal oxidation to alcohols, which are further oxidized by alcohol and aldehyde dehydrogenases, whose products can enter β-oxidation pathways. B. bassiana contains at least 83 genes coding for cytochrome P450s (CYP), a subset of which are involved in hydrocarbon oxidation, and several of which represent new CYP subfamilies/families. Expression data indicated differential induction by alkanes and insect lipids and four CYP proteins have been partially characterized after heterologous expression in yeast. Gene knockouts revealed a phenotype for only one (cyp52X1) out of six genes examined to date. CYP52X1 oxidizes long chain fatty acids and participates in the degradation of specific epicuticular lipid components needed for breaching the insect waxy layer. Examining the hydrocarbon oxidizing CYP repertoire of pathogens involved in insect epicuticle degradation can lead to the characterization of enzymes with novel substrate specificities. Pathogen targeting may also represent an important co-evolutionary process regarding insect cuticular hydrocarbon

  13. Antioxidant and Antiradical Activities of Manihot esculenta Crantz (Euphorbiaceae) Leaves and Other Selected Tropical Green Vegetables Investigated on Lipoperoxidation and Phorbol-12-myristate-13-acetate (PMA) Activated Monocytes

    PubMed Central

    Tsumbu, Cesar N.; Deby-Dupont, Ginette; Tits, Monique; Angenot, Luc; Franck, Thierry; Serteyn, Didier; Mouithys-Mickalad, Ange

    2011-01-01

    Abelmoschus esculentus (Malvaceae), Hibiscus acetosella (Malvaceae), Manihot esculenta Crantz (Euphorbiaceae) and Pteridium aquilinum (Dennstaedtiaceae) leaves are currently consumed as vegetables by migrants from sub-Saharan Africa living in Western Europe and by the people in the origin countries, where these plants are also used in the folk medicine. Manihot leaves are also eaten in Latin America and some Asian countries. This work investigated the capacity of aqueous extracts prepared from those vegetables to inhibit the peroxidation of a linoleic acid emulsion. Short chain, volatile C-compounds as markers of advanced lipid peroxidation were measured by gas chromatography by following the ethylene production. The generation of lipid hydroperoxides, was monitored by spectroscopy using N-N′-dimethyl-p-phenylene-diamine (DMPD). The formation of intermediate peroxyl, and other free radicals, at the initiation of the lipid peroxidation was investigated by electron spin resonance, using α-(4-pyridyl-1-oxide)-N-tert-butylnitrone as spin trap agent. The ability of the extracts to decrease the cellular production of reactive oxygen species (ROS) in “inflammation like” conditions was studied by fluorescence technique using 2′,7′-dichlorofluorescine-diacetate as fluorogenic probe, in a cell model of human monocytes (HL-60 cells) activated with phorbol ester. Overall the extracts displayed efficient concentration-dependent inhibitory effects. Their total polyphenol and flavonoid content was determined by classic colorimetric methods. An HPLC-UV/DAD analysis has clearly identified the presence of some polyphenolic compounds, which explains at least partially the inhibitions observed in our models. The role of these plants in the folk medicine by sub-Saharan peoples as well as in the prevention of oxidative stress and ROS related diseases requires further consideration. PMID:22254126

  14. Identification and biochemical characterization of polyamine oxidases in amphioxus: Implications for emergence of vertebrate-specific spermine and acetylpolyamine oxidases.

    PubMed

    Wang, Huihui; Liu, Baobao; Li, Hongyan; Zhang, Shicui

    2016-01-10

    Polyamine oxidases (PAOs) have been identified in a wide variety of animals, as well as in fungi and plant. Generally, plant PAOs oxidize spermine (Spm), spermidine (Spd) and their acetylated derivatives, N(1)-acetylspermine (N(1)-Aspm) and N(1)-acetylspermidine (N(1)-Aspd), while yeast PAOs oxidize Spm, N(1)-Aspm and N(1)-Aspd, but not Spd. By contrast, two different enzymes, namely spermine oxidase (SMO) and acetylpolyamine oxidase (APAO), specifically catalyze the oxidation of Spm and N(1)-Aspm/N(1)-Aspd, respectively. However, our knowledge on the biochemical and structural characterization of PAOs remains rather limited, and their evolutionary history is still enigmatic. In this study, two amphioxus (Branchiostoma japonicum) PAO genes, named Bjpao1 and Bjpao2, were cloned and characterized. Both Bjpao1 and Bjpao2 displayed distinct tissue-specific expression patterns. Notably, rBjPAO1 oxidized both spermine and spermidine, but not N(1)-acetylspermine, whereas rBjPAO2 oxidizes both spermidine and N(1)-acetylspermine, but not spermine. To understand structure-function relationship, the enzymatic activities of mutant BjPAOs that were generated by site-directed mutagenesis and expressed in E. coli were examined, The results indicate that the residues H64, K301 and T460 in rBjPAO1, and H69, K315 and T467 in rBjPAO2 were all involved in substrate binding and enzyme catalytic activity to some extent. Based on our results and those of others, a model depicting the divergent evolution and functional specialization of vertebrate SMO and APAO genes is proposed.

  15. Oxidation of Inconel 625 superalloy upon treatment with oxygen or hydrogen plasma at high temperature

    NASA Astrophysics Data System (ADS)

    Vesel, Alenka; Drenik, Aleksander; Elersic, Kristina; Mozetic, Miran; Kovac, Janez; Gyergyek, Tomaz; Stockel, Jan; Varju, Jozef; Panek, Radomir; Balat-Pichelin, Marianne

    2014-06-01

    Initial stages of Inconel 625 superalloy (Ni60Cr30Mo10Ni4Nb1) oxidation upon short treatment with gaseous plasma at different temperatures up to about 1600 K were studied. Samples were treated for different periods up to a minute by oxygen or hydrogen plasma created with a microwave discharge in the standing-wave mode at a pressure of 40 Pa and a power 500 W. Simultaneous heating of the samples was realized by focusing concentrated solar radiation from a 5 kW solar furnace directly onto the samples. The morphological changes upon treatment were monitored using scanning electron microscopy, compositional depth profiling was performed using Auger electron spectroscopy, while structural changes were determined by X-ray diffraction. The treatment in oxygen plasma caused formation of metal oxide clusters of three dimensional crystallites initially rich in nickel oxide with the increasing chromium oxide content as the temperature was increasing. At about 1100 K iron and niobium oxides prevailed on the surface causing a drop of the material emissivity at 5 μm. Simultaneously the NiCr2O4 compound started growing at the interface between the oxide film and bulk alloy and the compound persisted up to temperatures close to the Inconel melting point. Intensive migration of minority alloying elements such as Fe and Ti was observed at 1600 K forming mixed surface oxides of sub-micrometer dimensions. The treatment in hydrogen plasma with small admixture of water vapor did not cause much modification unless the temperature was close to the melting point. At such conditions aluminum segregated on the surface and formed well-defined Al2O3 crystals.

  16. The enzymic oxidation of chlorogenic acid and some reactions of the quinone produced

    PubMed Central

    Pierpoint, W. S.

    1966-01-01

    1. Partially purified preparations of tobacco-leaf o-diphenol oxidase (o-quinol–oxygen oxidoreductase; EC 1.10.3.1) oxidize chlorogenic acid to brown products, absorbing, on average, 1·6atoms of oxygen/mol. oxidized, and evolving a little carbon dioxide. 2. The effect of benzenesulphinic acid on the oxidation suggests that the first stage is the formation of a quinone; the solution does not go brown, oxygen uptake is restricted to 1 atom/mol. oxidized, and a compound is produced whose composition corresponds to that of a sulphone of the quinone derived from chlorogenic acid. 3. Several other compounds that react with quinones affect the oxidation of chlorogenic acid. The colour of the products formed and the oxygen absorbed in their formation suggest that the quinone formed in the oxidation reacts with these compounds in the same way as do simpler quinones. 4. Some compounds that are often used to prevent the oxidation of polyphenols were tested to see if they act by inhibiting o-diphenol oxidase, by reacting with quinone intermediates, or both. 5. Ascorbate inhibits the enzyme and also reduces the quinone. 6. Potassium ethyl xanthate, diethyldithiocarbamate and cysteine inhibit the enzyme to different extents, and also react with the quinone. The nature of the reaction depends on the relative concentrations of inhibitor and chlorogenic acid. Excess of inhibitor prevents the solution from turning brown and restricts oxygen uptake to 1 atom/mol. of chlorogenic acid oxidized; smaller amounts do not prevent browning and slightly increase oxygen uptake. 7. 2-Mercaptobenzothiazole inhibits the enzyme, and also probably reacts with the quinone; inhibited enzyme is reactivated as if the inhibitor is removed as traces of quinone are produced. 8. Thioglycollate and polyvinylpyrrolidone inhibit the enzyme. Thioglycollate probably reduces the quinone to a small extent. PMID:5941350

  17. Theoretical study on the mechanism of Ni-catalyzed alkyl-alkyl Suzuki cross-coupling.

    PubMed

    Li, Zhe; Jiang, Yuan-Ye; Fu, Yao

    2012-04-01

    Ni-catalyzed cross-coupling of unactivated secondary alkyl halides with alkylboranes provides an efficient way to construct alkyl-alkyl bonds. The mechanism of this reaction with the Ni/L1 (L1=trans-N,N'-dimethyl-1,2-cyclohexanediamine) system was examined for the first time by using theoretical calculations. The feasible mechanism was found to involve a Ni(I)-Ni(III) catalytic cycle with three main steps: transmetalation of [Ni(I)(L1)X] (X=Cl, Br) with 9-borabicyclo[3.3.1]nonane (9-BBN)R(1) to produce [Ni(I)(L1)(R(1))], oxidative addition of R(2) X with [Ni(I)(L1)(R(1))] to produce [Ni(III)(L1)(R(1))(R(2))X] through a radical pathway, and C-C reductive elimination to generate the product and [Ni(I)(L1)X]. The transmetalation step is rate-determining for both primary and secondary alkyl bromides. KOiBu decreases the activation barrier of the transmetalation step by forming a potassium alkyl boronate salt with alkyl borane. Tertiary alkyl halides are not reactive because the activation barrier of reductive elimination is too high (+34.7 kcal mol(-1)). On the other hand, the cross-coupling of alkyl chlorides can be catalyzed by Ni/L2 (L2=trans-N,N'-dimethyl-1,2-diphenylethane-1,2-diamine) because the activation barrier of transmetalation with L2 is lower than that with L1. Importantly, the Ni(0)-Ni(II) catalytic cycle is not favored in the present systems because reductive elimination from both singlet and triplet [Ni(II)(L1)(R(1))(R(2))] is very difficult.

  18. Free radical production from the interaction of 2-chloroethyl vesicants (mustard gas) with pyridine nucleotide-driven flavoprotein electron transport systems

    SciTech Connect

    Brimfield, A.A. Mancebo, A.M.; Mason, R.P.; Jiang, J.J.; Siraki, A.G.; Novak, M.J.

    2009-01-01

    The biochemical sequelae to chloroethyl mustard exposure correspond very well to toxic processes initiated by free radicals. Additionally, mustard solutions contain spontaneously formed cyclic onium ions which produce carbon free radicals when reduced electrochemically. Therefore, we hypothesized that the onium ions of sulfur or nitrogen mustards might produce carbon free radicals upon being reduced enzymatically, and that these radicals might constitute a metabolic activation. We set out to document radical production using an in vitro metabolic system and electron paramagnetic resonance (EPR). Our system consisted of NADPH, one of several pyridine nucleotide-driven flavoprotein reductases, cytochrome c as a terminal electron acceptor, various sulfur or nitrogen mustards and the spin trap {alpha}-[4-pyridyl-1-oxide]-N-tert-butylnitrone in buffer. Reactions were started by adding the reductase to the other materials, vortexing and immediately transferring the mixture to a 10 mm EPR flat cell. Repeated scans on a Bruker ESP 300E EPR spectrometer produced a triplet of doublets with hyperfine splitting constants of a{sub N} = 15.483 G and a{sub H} = 2.512 G. The outcome supported our hypothesis that carbon-centered free radicals are produced when mustard-related onium ions are enzymatically reduced. The EPR results varied little with the chloroethyl compound used or with porcine or human cytochrome P450 reductase, the reductase domain of rat brain neuronal nitric oxide synthase or rat liver thioredoxin reductase. Our results offer new insight into the basis for mustard-induced vesication and the outcome of exposure to different mustards. The free radical model provides an explanation for similarities in the lesions arising from mustard exposure and energy-based lesions such as those from heat, ultraviolet and nuclear radiation as well as damage across tissue types such as skin, eyes or airway epithelium.

  19. Antioxidant and antiradical activities of Manihot esculenta Crantz (Euphorbiaceae) leaves and other selected tropical green vegetables investigated on lipoperoxidation and phorbol-12-myristate-13-acetate (PMA) activated monocytes.

    PubMed

    Tsumbu, Cesar N; Deby-Dupont, Ginette; Tits, Monique; Angenot, Luc; Franck, Thierry; Serteyn, Didier; Mouithys-Mickalad, Ange

    2011-09-01

    Abelmoschus esculentus (Malvaceae), Hibiscus acetosella (Malvaceae), Manihot esculenta Crantz (Euphorbiaceae) and Pteridium aquilinum (Dennstaedtiaceae) leaves are currently consumed as vegetables by migrants from sub-Saharan Africa living in Western Europe and by the people in the origin countries, where these plants are also used in the folk medicine. Manihot leaves are also eaten in Latin America and some Asian countries. This work investigated the capacity of aqueous extracts prepared from those vegetables to inhibit the peroxidation of a linoleic acid emulsion. Short chain, volatile C-compounds as markers of advanced lipid peroxidation were measured by gas chromatography by following the ethylene production. The generation of lipid hydroperoxides, was monitored by spectroscopy using N-N'-dimethyl-p-phenylene-diamine (DMPD). The formation of intermediate peroxyl, and other free radicals, at the initiation of the lipid peroxidation was investigated by electron spin resonance, using α-(4-pyridyl-1-oxide)-N-tert-butylnitrone as spin trap agent. The ability of the extracts to decrease the cellular production of reactive oxygen species (ROS) in "inflammation like" conditions was studied by fluorescence technique using 2',7'-dichlorofluorescine-diacetate as fluorogenic probe, in a cell model of human monocytes (HL-60 cells) activated with phorbol ester. Overall the extracts displayed efficient concentration-dependent inhibitory effects. Their total polyphenol and flavonoid content was determined by classic colorimetric methods. An HPLC-UV/DAD analysis has clearly identified the presence of some polyphenolic compounds, which explains at least partially the inhibitions observed in our models. The role of these plants in the folk medicine by sub-Saharan peoples as well as in the prevention of oxidative stress and ROS related diseases requires further consideration.

  20. Modification of High Density Lipoprotein by Myeloperoxidase Generates a Pro-inflammatory Particle*

    PubMed Central

    Undurti, Arundhati; Huang, Ying; Lupica, Joseph A.; Smith, Jonathan D.; DiDonato, Joseph A.; Hazen, Stanley L.

    2009-01-01

    High density lipoprotein (HDL) is the major atheroprotective particle in plasma. Recent studies demonstrate that myeloperoxidase (MPO) binds to HDL in vivo, selectively targeting apolipoprotein A1 (apoA1) of HDL for oxidative modification and concurrent loss in cholesterol efflux and lecithin cholesterol acyl transferase activating activities, generating a “dysfunctional HDL” particle. We now show that (patho)physiologically relevant levels of MPO-catalyzed oxidation result in loss of non-cholesterol efflux activities of HDL including anti-apoptotic and anti-inflammatory functions. One mechanism responsible is shown to involve the loss of modified HDL binding to the HDL receptor, scavenger receptor B1, and concurrent acquisition of saturable and specific binding to a novel unknown receptor independent of scavenger receptors CD36 and SR-A1. HDL modification by MPO is further shown to confer pro-inflammatory gain of function activities as monitored by NF-κB activation and surface vascular cell adhesion molecule levels on aortic endothelial cells exposed to MPO-oxidized HDL. The loss of non-cholesterol efflux activities and the gain of pro-inflammatory functions requires modification of the entire particle and can be recapitulated by oxidation of reconstituted HDL particles comprised of apoA1 and nonoxidizable phosphatidylcholine species. Multiple site-directed mutagenesis studies of apoA1 suggest that the pro-inflammatory activity of MPO-modified HDL does not involve methionine, tyrosine, or tryptophan, oxidant-sensitive residues previously mapped as sites of apoA1 oxidation within human atheroma. Thus, MPO-catalyzed oxidation of HDL results not only in the loss of classic atheroprotective reverse cholesterol transport activities of the lipoprotein but also both the loss of non-cholesterol efflux related activities and the gain of pro-inflammatory functions. PMID:19726691

  1. Tryptophan contributions to the unusual circular dichroism of fd bacteriophage.

    PubMed

    Arnold, G E; Day, L A; Dunker, A K

    1992-09-01

    The circular dichroism (CD) spectrum of fd bacteriophage has a deep minimum at 222 nm characteristic of highly alpha-helical protein, but there is a shoulder at 208 nm rather than a minimum, with a 222/208-nm amplitude ratio near 1.5 rather than near 1. Oxidation of fd phage with the tryptophan reagent N-bromosuccinimide (NBS) changes the ratio. In this report, the NBS titration of fd is followed by CD and three other spectroscopies, the results of which yield an explanation of the unusual CD spectrum. Absorbance, fluorescence, and Raman data show the oxidation to have two phases, the first of which involves the destruction of tryptophan and the second, tryptophan and tyrosine. Raman spectra reveal the invariance of an environmentally-sensitive tyrosine Fermi resonance doublet during the first oxidative phase. Raman spectra also show that little or no change of alpha-helicity occurs in the first or second oxidation phase, although very slight changes in the helix parameters might be occurring. Concurrent with the destruction of tryptophan during the first phase is the appearance in CD difference spectra ([theta]NBS-treated fd - [theta]native fd) of positive maxima at 208-210 nm and negative maxima at 224 nm, with crossovers at 217 nm. Enormous difference ellipticities, per oxidized subunit of 50 amino acids, of +490,000 +/- 80,000 deg cm2 dmol-1 at 208 nm and -520,000 +/- 110,000 deg cm2 dmol-1 at 224 nm have been derived from the data.(ABSTRACT TRUNCATED AT 250 WORDS)

  2. Reactive oxygen species are involved in regulation of pollen wall cytomechanics.

    PubMed

    Smirnova, A V; Matveyeva, N P; Yermakov, I P

    2014-01-01

    Production and scavenging of reactive oxygen species (ROS) in somatic plant cells is developmentally regulated and plays an important role in the modification of cell wall mechanical properties. Here we show that H2O2 and the hydroxyl radical ((•)OH) can regulate germination of tobacco pollen by modifying the mechanical properties of the pollen intine (inner layer of the pollen wall). Pollen germination was affected by addition of exogenous H2O2, (•)OH, and by antioxidants scavenging endogenous ROS: superoxide dismutase, superoxide dismutase/catalase mimic Mn-5,10,15,20-tetrakis(1-methyl-4-pyridyl)21H, 23H-porphin, or a spin-trap α-(4-pyridyl-1-oxide)-N-tert-butylnitrone, which eliminates (•)OH. The inhibiting concentrations of exogenous H2O2 and (•)OH did not decrease pollen viability, but influenced the mechanical properties of the wall. The latter were estimated by studying the resistance of pollen to hypo-osmotic shock. (•)OH caused excess loosening of the intine all over the surface of the pollen grain, disrupting polar growth induction. In contrast, H2O2, as well as partial removal of endogenous (•)OH, over-tightened the wall, impeding pollen tube emergence. Feruloyl esterase (FAE) was used as a tool to examine whether H2O2-inducible inter-polymer cross-linking is involved in the intine tightening. FAE treatment caused loosening of the intine and stimulated pollen germination and pollen tube growth, revealing ferulate cross-links in the intine. Taken together, the data suggest that pollen intine properties can be regulated differentially by ROS. (•)OH is involved in local loosening of the intine in the germination pore region, while H2O2 is necessary for intine strengthening in the rest of the wall through oxidative coupling of feruloyl polysaccharides.

  3. Desulfonatronobacter acidivorans gen. nov., sp. nov. and Desulfobulbus alkaliphilus sp. nov., haloalkaliphilic heterotrophic sulfate-reducing bacteria from soda lakes.

    PubMed

    Sorokin, Dimitry Yu; Tourova, Tatjana P; Panteleeva, Anzhela N; Muyzer, Gerard

    2012-09-01

    Two types of heterotrophic sulfate-reducing bacteria (SRB) were isolated from anoxic sediments of hypersaline soda lakes in Kulunda Steppe (Altai, Russia). The isolates used propionate as an energy and carbon source. Strain APT2(T) was enriched and isolated with thiosulfate as the electron acceptor. Strains APS1(T) and ASS1 were isolated with sulfate. Strain APT2(T) was a short rod and motile with a single subpolar flagellum, while strains APS1(T) and ASS1 were lemon-shaped oval rods and motile with a single polar flagellum and thin flagella-like filaments. Strain APT2(T) grew by complete oxidation of C(3)-C(8) fatty acids with thiosulfate or sulfate as the electron acceptor, while strains APS1(T) and ASS1 were much less versatile and utilized only propionate and pyruvate as the electron donor and carbon source with sulfate or sulfite as the electron acceptor. Furthermore, strains APS1(T) and ASS1 oxidized propionate incompletely to form acetate. All of the isolates were moderately halophilic and obligately alkaliphilic. Phylogenetic analysis based on 16S rRNA gene sequences placed the isolates in the order Desulfobacterales of the class Deltaproteobacteria. Strain APT2(T) belonged to the family Desulfobacteraceae and clustered with a halophilic SRB, Desulfosalsimonas propionicica PropA(T). Strains APS1(T) and ASS1 were closely related to each other and clustered with the genus Desulfobulbus of the family Desulfobulbaceae. On the basis of phenotypic and phylogenetic analysis, the isolates are proposed to represent two novel taxa, Desulfonatronobacter acidivorans gen. nov., sp. nov. (type strain of the type species APT2(T) = DSM 24257(T) = UNIQEM U853(T)) and Desulfobulbus alkaliphilus sp. nov. (type strain APS1(T) = DSM 24258(T) = UNIQEM U900(T)).

  4. Rapid reaction kinetics of proline dehydrogenase in the multifunctional proline utilization A protein.

    PubMed

    Moxley, Michael A; Becker, Donald F

    2012-01-10

    The multifunctional proline utilization A (PutA) flavoenzyme from Escherichia coli catalyzes the oxidation of proline to glutamate in two reaction steps using separate proline dehydrogenase (PRODH) and Δ(1)-pyrroline-5-carboxylate (P5C) dehydrogenase domains. Here, the kinetic mechanism of PRODH in PutA is studied by stopped-flow kinetics to determine microscopic rate constants for the proline:ubiquinone oxidoreductase mechanism. Stopped-flow data for proline reduction of the flavin cofactor (reductive half-reaction) and oxidation of reduced flavin by CoQ(1) (oxidative half-reaction) were best-fit by a double exponential from which maximum observable rate constants and apparent equilibrium dissociation constants were determined. Flavin semiquinone was not observed in the reductive or oxidative reactions. Microscopic rate constants for steps in the reductive and oxidative half-reactions were obtained by globally fitting the stopped-flow data to a simulated mechanism that includes a chemical step followed by an isomerization event. A microscopic rate constant of 27.5 s(-1) was determined for proline reduction of the flavin cofactor followed by an isomerization step of 2.2 s(-1). The isomerization step is proposed to report on a previously identified flavin-dependent conformational change [Zhang, W. et al. (2007) Biochemistry 46, 483-491] that is important for PutA functional switching but is not kinetically relevant to the in vitro mechanism. Using CoQ(1), a soluble analogue of ubiquinone, a rate constant of 5.4 s(-1) was obtained for the oxidation of flavin, thus indicating that this oxidative step is rate-limiting for k(cat) during catalytic turnover. Steady-state kinetic constants calculated from the microscopic rate constants agree with the experimental k(cat) and k(cat)/K(m) parameters.

  5. Competitive Degradation of Steroid Estrogens by Potassium Permanganate Combined with Ultrasound

    PubMed Central

    Deng, Jing; Tang, Kai; Zhu, Shijun; Ma, Xiaoyan; Zhang, Kejia; Song, Yali; Li, Xueyan; Li, Qingsong; Liu, Zhenhua; Zhou, Kejin

    2015-01-01

    The occurrence of natural estrogens including estrone (E1), 17β-estradiol (E2), and synthetic 17α-ethinylestradiol (EE2), which can be excreted by both humans and animals, and can enter the aqueous environment along with the discharge of domestic sewage, is a major concern since this may represent a serious health risk to humans even at extremely trace levels (ng·L−1). Simultaneous degradation of three coexisting steroid estrogens (SEs) in aqueous solutions by coupled ultrasound and KMnO4 systems (KMnO4/ultrasound) were investigated to find out whether there is a competitive degradation of multiple contaminants or not. Results indicate that the degradation ratios of target SEs were all more than 50% after 120 min reaction contact, greatly enhanced when compared with the single KMnO4 (2 mg·L−1) oxidation of E2 (37.0%), EE2 (34.4%), and E1 (34.0%), and the single sonochemical oxidation of E2 (37.1%), EE2 (31.1%), and E1 (29.7%). In the adopted processes, the degradations of SEs fit the first-order kinetic reaction, with different reaction rates. Kinetic parameters revealed there was little difference between coexisting SEs, which means there was almost no competitive degradation. The removal efficiency and degradation rate of SEs in natural water was higher than those in pure water, which suggested that the coupled KMnO4/ultrasound technology had prospective applications in the removal of complex contaminants in actual drinking water treatment. PMID:26690185

  6. Indole-3-acetaldoxime-derived compounds restrict root colonization in the beneficial interaction between Arabidopsis roots and the endophyte Piriformospora indica.

    PubMed

    Nongbri, Pyniarlang L; Johnson, Joy Michal; Sherameti, Irena; Glawischnig, Erich; Halkier, Barbara Ann; Oelmüller, Ralf

    2012-09-01

    The growth-promoting and root-colonizing endophyte Piriformospora indica induces camalexin and the expression of CYP79B2, CYP79B3, CYP71A13, PAD3, and WRKY33 required for the synthesis of indole-3-acetaldoxime (IAOx)-derived compounds in the roots of Arabidopsis seedlings. Upregulation of the mRNA levels by P. indica requires cytoplasmic calcium elevation and mitogen-activated protein kinase 3 but not root-hair-deficient 2, radical oxygen production, or the 3-phosphoinositide-dependent kinase 1/oxidative signal-inducible 1 pathway. Because P. indica-mediated growth promotion is impaired in cyp79B2 cyp79B3 seedlings, while pad3 seedlings-which do not accumulate camalexin-still respond to the fungus, IAOx-derived compounds other than camalexin (e.g., indole glucosinolates) are required during early phases of the beneficial interaction. The roots of cyp79B2 cyp79B3 seedlings are more colonized than wild-type roots, and upregulation of the defense genes pathogenesis-related (PR)-1, PR-3, PDF1.2, phenylalanine ammonia lyase, and germin indicates that the mutant responds to the lack of IAOx-derived compounds by activating other defense processes. After 6 weeks on soil, defense genes are no longer upregulated in wild-type, cyp79B2 cyp79B3, and pad3 roots. This results in uncontrolled fungal growth in the mutant roots and reduced performance of the mutants. We propose that a long-term harmony between the two symbionts requires restriction of root colonization by IAOx-derived compounds.

  7. Chronic low-dose γ-irradiation of Drosophila melanogaster larvae induces gene expression changes and enhances locomotive behavior

    PubMed Central

    Kim, Cha Soon; Seong, Ki Moon; Lee, Byung Sub; Lee, In Kyung; Yang, Kwang Hee; Kim, Ji-Young; Nam, Seon Young

    2015-01-01

    Although radiation effects have been extensively studied, the biological effects of low-dose radiation (LDR) are controversial. This study investigates LDR-induced alterations in locomotive behavior and gene expression profiles of Drosophila melanogaster. We measured locomotive behavior using larval pupation height and the rapid iterative negative geotaxis (RING) assay after exposure to 0.1 Gy γ-radiation (dose rate of 16.7 mGy/h). We also observed chronic LDR effects on development (pupation and eclosion rates) and longevity (life span). To identify chronic LDR effects on gene expression, we performed whole-genome expression analysis using gene-expression microarrays, and confirmed the results using quantitative real-time PCR. The pupation height of the LDR-treated group at the first larval instar was significantly higher (∼2-fold increase in PHI value, P < 0.05). The locomotive behavior of LDR-treated male flies (∼3 − 5 weeks of age) was significantly increased by 7.7%, 29% and 138%, respectively (P < 0.01), but pupation and eclosion rates and life spans were not significantly altered. Genome-wide expression analysis identified 344 genes that were differentially expressed in irradiated larvae compared with in control larvae. We identified several genes belonging to larval behavior functional groups such as locomotion (1.1%), oxidation reduction (8.0%), and genes involved in conventional functional groups modulated by irradiation such as defense response (4.9%), and sensory and perception (2.5%). Four candidate genes were confirmed as differentially expressed genes in irradiated larvae using qRT-PCR (>2-fold change). These data suggest that LDR stimulates locomotion-related genes, and these genes can be used as potential markers for LDR. PMID:25792464

  8. Oxidized Docosahexaenoic Acid Species and Lipid Peroxidation Products Increase Amyloidogenic Amyloid Precursor Protein Processing.

    PubMed

    Grimm, Marcus O W; Haupenthal, Viola J; Mett, Janine; Stahlmann, Christoph P; Blümel, Tamara; Mylonas, Nadine T; Endres, Kristina; Grimm, Heike S; Hartmann, Tobias

    2016-01-01

    One of the main characteristics of Alzheimer's disease (AD) is the β-amyloid peptide (Aβ) generated by β- and γ-secretase processing of the amyloid precursor protein (APP). Previously it has been demonstrated that polyunsaturated fatty acids (PUFAs), especially docosahexaenoic acid (DHA), are associated with a reduced risk of AD caused by decreased Aβ production. However, in epidemiological studies and nutritional approaches, the outcomes of DHA-dependent treatment were partially controversial. PUFAs are very susceptible to reactive oxygen species and lipid peroxidation, which are increased during disease pathology. In line with published results, lipid peroxidation was elevated in human postmortem AD brains; especially 4-hydroxy-nonenal (HNE) was increased. To investigate whether lipid peroxidation is only a consequence or might also influence the processes leading to AD, we analyzed 7 different oxidized lipid species including 5 oxidized DHA derivatives and the lipid peroxidation products of ω-3 and ω-6 PUFAs, HNE and 4-hydroxy-hexenal, in human neuroblastoma cells and mouse mixed cortical neurons. In the presence of oxidized lipids Aβ and soluble β-secreted APP levels were elevated, whereas soluble α-secreted APP was decreased, suggesting a shift from the nonamyloidogenic to the amyloidogenic pathway of APP processing. Furthermore, β- and γ-secretase activity was increased by oxidized lipids via increased gene expression and additionally by a direct effect on β-secretase activity. Importantly, only 1% oxidized DHA was sufficient to revert the protective effect of DHA and to significantly increase Aβ production. Therefore, our results emphasize the need to prevent DHA from oxidation in nutritional approaches and might help explain the divergent results of clinical DHA studies. PMID:26642316

  9. Tobacco smoke aging in the presence of ozone: A room-sized chamber study

    NASA Astrophysics Data System (ADS)

    Petrick, Lauren M.; Sleiman, Mohamad; Dubowski, Yael; Gundel, Lara A.; Destaillats, Hugo

    2011-09-01

    Exposure to tobacco pollutants that linger indoors after smoking has taken place ( thirdhand smoke, THS) can occur over extended periods and is modulated by chemical processes involving atmospheric reactive species. This study investigates the role of ozone and indoor surfaces in chemical transformations of tobacco smoke residues. Gas and particle constituents of secondhand smoke (SHS) as well as sorbed SHS on chamber internal walls and model materials (cotton, paper, and gypsum wallboard) were characterized during aging. After smoldering 10 cigarettes in a 24-m 3 room size chamber, gas-phase nicotine was rapidly removed by sorption to chamber surfaces, and subsequently re-emitted during ventilation with clean air to a level of ˜10% that during the smoking phase. During chamber ventilation in the presence of ozone (180 ppb), ozone decayed at a rate of 5.6 h -1 and coincided with a factor of 5 less nicotine sorbed to wallboard. In the presence of ozone, no gas phase nicotine was detected as a result of re-emission, and higher concentrations of nicotine oxidation products were observed than when ventilation was performed with ozone-free air. Analysis of the model surfaces showed that heterogeneous nicotine-ozone reaction was faster on paper than cotton, and both were faster than on wallboard. However, wallboard played a dominant role in ozone-initiated reaction in the chamber due to its large total geometric surface area and sink potential compared to the other substrates. This study is the first to show in a room-sized environmental chamber that the heterogeneous ozone chemistry of sorbed nicotine generates THS constituents of concern, as observed previously in bench-top studies. In addition to the main oxidation products (cotinine, myosmine and N-methyl formamide), nicotine-1-oxide was detected for the first time.

  10. Apocynin and Nox2 regulate NF-κB by modifying thioredoxin-1 redox-state

    PubMed Central

    Trevelin, Silvia Cellone; dos Santos, Célio Xavier; Ferreira, Raphael Gomes; de Sá Lima, Larissa; Silva, Rangel Leal; Scavone, Cristoforo; Curi, Rui; Alves-Filho, José Carlos; Cunha, Thiago Mattar; Roxo-Júnior, Pérsio; Cervi, Maria-Célia; Laurindo, Francisco Rafael Martins; Hothersall, John Stephen; Cobb, Andrew M.; Zhang, Min; Ivetic, Aleksandar; Shah, Ajay M.; Lopes, Lucia Rossetti; Cunha, Fernando Queiroz

    2016-01-01

    The reactive-oxygen-species-(ROS)-generating-enzyme Nox2 is essential for leukocyte anti-microbial activity. However its role in cellular redox homeostasis and, consequently, in modulating intracellular signaling pathways remains unclear. Herein, we show Nox2 activation favors thioredoxin-1 (TRX-1)/p40phox interaction, which leads to exclusion of TRX-1 from the nucleus. In contrast, the genetic deficiency of Nox2 or its pharmacological inhibition with apocynin (APO) results in reductive stress after lipopolysaccharide-(LPS)-cell stimulation, which causes nuclear accumulation of TRX-1 and enhanced transcription of inflammatory mediators through nuclear-factor-(NF)-κB. The NF-κB overactivation is prevented by TRX-1 oxidation using inhibitors of thioredoxin reductase-1 (TrxR-1). The Nox2/TRX-1/NF-κB intracellular signaling pathway is involved in the pathophysiology of chronic granulomatous disease (CGD) and sepsis. In fact, TrxR-1 inhibition prevents nuclear accumulation of TRX-1 and LPS-stimulated hyperproduction of tumor-necrosis-factor-(TNF)-α by monocytes and neutrophils purified from blood of CGD patients, who have deficient Nox2 activity. TrxR-1 inhibitors, either lanthanum chloride (LaCl3) or auranofin (AUR), also increase survival rates of mice undergoing cecal-ligation-and-puncture-(CLP). Therefore, our results identify a hitherto unrecognized Nox2-mediated intracellular signaling pathway that contributes to hyperinflammation in CGD and in septic patients. Additionally, we suggest that TrxR-1 inhibitors could be potential drugs to treat patients with sepsis, particularly in those with CGD. PMID:27698473

  11. Modern marine sediments as a natural analog to the chemically stressed environment of a landfill

    USGS Publications Warehouse

    Baedecker, M.J.; Back, W.

    1979-01-01

    Chemical reactions that occur in landfills are analogous to those reactions that occur in marine sediments. Lateral zonation of C, N, S, O, H, Fe and Mn species in landfills is similar to the vertical zonation of these species in marine sediments and results from the following reaction sequence: (1) oxidation of C, N and S species in the presence of dissolved free oxygen to HCO3-, NO3- and SO2-4; (2) after consumption of molecular oxygen, then NO3- is reduced, and Fe and Mn are solubilized; (3) SO2-4 is reduced to sulfide; and (4) organic compounds become the source of oxygen, and CH4 and NH4+ are formed as fermentation products. In a landfill in Delaware the oxidation potential increases downgradient and the redox zones in the reducing plume are characterized by: CH4, NH4+, Fe2+. Mn2+, HCO3- and NO3-. Lack of SO2-4 at that landfill eliminates the sulfide zone. Although it has not been observed at landfills, mineral alteration should result in precipitation of pyrite and/or siderite downgradient. Controls on the pH of leachate are the relative rates of production of HCO3-, NH4+ and CH4. Production of methane by fermentation at landfills results in 13C isotope fractionation and the accumulation of isotopically heavy ??CO2 (+10 to +18??? PDB). Isotope measurements may be useful to determine the extent of CO2 reduction in landfills and extent of dilution downgradient. The boundaries of reaction zones in stressed aquifers are determined by head distribution and flow velocity. Thus, if the groundwater flow is rapid relative to reaction rates, redox zones will develop downgradient. Where groundwater flow velocities are low the zones will overlap to the extent that they may be indeterminate. ?? 1979.

  12. Oxidative reactions during early stages of beer brewing studied by electron spin resonance and spin trapping.

    PubMed

    Frederiksen, Anne M; Festersen, Rikke M; Andersen, Mogens L

    2008-09-24

    An electron spin resonance (ESR)-based method was used for evaluating the levels of radical formation during mashing and in sweet wort. The method included the addition of 5% (v/v) ethanol together with the spin trap alpha-4-pyridyl(1-oxide)- N- tert-butylnitrone (POBN) to wort, followed by monitoring the rate of formation of POBN spin adducts during aerobic heating of the wort. The presence of ethanol makes the spin trapping method more selective and sensitive for the detection of highly reactive radicals such as hydroxyl and alkoxyl radicals. Samples of wort that were collected during the early stages of the mashing process gave higher rates of spin adduct formation than wort samples collected during the later stages. The lower oxidative stability of the early wort samples was confirmed by measuring the rate of oxygen consumption during heating of the wort. The addition of Fe(II) to the wort samples increased the rate of spin adduct formation, whereas the addition of Fe(II) during the mashing had no effect on the oxidative stability of the wort samples. Analysis of the iron content in the sweet wort samples demonstrated that iron added during the mashing had no effect on the iron level in the wort. The moderate temperatures during the early steps of mashing allow the endogenous malt enzymes to be active. The potential antioxidative effects of different redox-active enzymes during mashing were tested by measuring the rate of spin adduct formation in samples of wort. Surprisingly, a high catalase dosage caused a significant, 20% reduction of the initial rate of radical formation, whereas superoxide dismutase had no effect on the oxidation rates. This suggests that hydrogen peroxide and superoxide are not the only intermediates that play a role in the oxidative reactions occurring during aerobic oxidation of sweet wort.

  13. Consumer perception and sensory effect of oxidation in savory-flavored yogurt enriched with n-3 lipids.

    PubMed

    Rognlien, M; Duncan, S E; O'Keefe, S F; Eigel, W N

    2012-04-01

    The objective of this study was to determine the effects of different oils (butter, fish, and oxidized fish) on sensory characteristics of a savory [chile-lime (CL)] low-fat yogurt using descriptive (unstructured line scales, 5 attributes) and affective (hedonic) sensory testing methods. Yogurts were each manufactured at low [1.1-1.2% total fat; 0.43% added oil (wt/wt)] or high [1.6% total fat; 1% added oil (wt/wt)] levels of fish oil, with high levels of fish oil targeted to deliver 145 mg of docosahexaenoic acid+eicosapentaenoic acid/170 g of yogurt. In a preliminary study, untrained panelists (n=31), using triangle tests, did not discriminate between low levels of fish and butter oils in unflavored yogurts but could discern yogurt with oxidized fish oil, even at the low level. Trained panelists (n=12) described lower lime and acid flavor characteristics in CL-flavored yogurts containing 1% oxidized fish oil compared with yogurts containing low levels of oxidized fish oil and low or high levels of butter and fish oils. Oxidized flavor was higher in CL-flavored yogurts with oxidized fish oil (low and high) and with the high level of fish oil. Consumer ratings (n=100; 9-point hedonic scale; 9="like extremely) of overall acceptability and flavor acceptability were bimodally distributed, with overall means between 4 and 5 ("neither like nor dislike") for CL-flavored yogurt with butter or fish oils (high level). The upper 50% of responses for yogurt with butter or fish oil were 6.51 and 6.31, respectively, for overall acceptability ("like slightly"), and 7.02 and 6.56, respectively, for flavor acceptability. A large segment of consumers may be interested in incorporating heart-healthy n-3 lipids in their diets through frequent consumption of a savory yogurt enriched with n-3 fatty acids.

  14. Effects of ocean acidification on the swimming ability, development and biochemical responses of sand smelt larvae.

    PubMed

    Silva, Cátia S E; Novais, Sara C; Lemos, Marco F L; Mendes, Susana; Oliveira, Ana P; Gonçalves, Emanuel J; Faria, Ana M

    2016-09-01

    Ocean acidification, recognized as a major threat to marine ecosystems, has developed into one of the fastest growing fields of research in marine sciences. Several studies on fish larval stages point to abnormal behaviours, malformations and increased mortality rates as a result of exposure to increased levels of CO2. However, other studies fail to recognize any consequence, suggesting species-specific sensitivity to increased levels of CO2, highlighting the need of further research. In this study we investigated the effects of exposure to elevated pCO2 on behaviour, development, oxidative stress and energy metabolism of sand smelt larvae, Atherina presbyter. Larvae were caught at Arrábida Marine Park (Portugal) and exposed to different pCO2 levels (control: ~600μatm, pH=8.03; medium: ~1000μatm, pH=7.85; high: ~1800μatm, pH=7.64) up to 15days, after which critical swimming speed (Ucrit), morphometric traits and biochemical biomarkers were determined. Measured biomarkers were related with: 1) oxidative stress - superoxide dismutase and catalase enzyme activities, levels of lipid peroxidation and DNA damage, and levels of superoxide anion production; 2) energy metabolism - total carbohydrate levels, electron transport system activity, lactate dehydrogenase and isocitrate dehydrogenase enzyme activities. Swimming speed was not affected by treatment, but exposure to increasing levels of pCO2 leads to higher energetic costs and morphometric changes, with larger larvae in high pCO2 treatment and smaller larvae in medium pCO2 treatment. The efficient antioxidant response capacity and increase in energetic metabolism only registered at the medium pCO2 treatment may indicate that at higher pCO2 levels the capacity of larvae to restore their internal balance can be impaired. Our findings illustrate the need of using multiple approaches to explore the consequences of future pCO2 levels on organisms.

  15. Geothermometry of Kilauea Iki lava lake, Hawaii

    USGS Publications Warehouse

    Helz, R.T.; Thornber, C.R.

    1987-01-01

    Data on the variation of temperature with time and in space are essential to a complete understanding of the crystallization history of basaltic magma in Kilauea Iki lava lake. Methods used to determine temperatures in the lake have included direct, downhole thermocouple measurements and Fe-Ti oxide geothermometry. In addition, the temperature variations of MgO and CaO contents of glasses, as determined in melting experiments on appropriate Kilauean samples, have been calibrated for use as purely empirical geothermometers and are directly applicable to interstitial glasses in olivine-bearing core from Kilauea Iki. The uncertainty in inferred quenching temperatures is ??8-10?? C. Comparison of the three methods shows that (1) oxide and glass geothermometry give results that are consistent with each other and consistent with the petrography and relative position of samples, (2) downhole thermo-couple measurements are low in all but the earliest, shallowest holes because the deeper holes never completely recover to predrilling temperatures, (3) glass geothermometry provides the greatest detail on temperature profiles in the partially molten zone, much of which is otherwise inaccessible, and (4) all three methods are necessary to construct a complete temperature profile for any given drill hole. Application of glass-based geothermometry to partially molten drill core recovered in 1975-1981 reveals in great detail the variation of temperature, in both time and space, within the partially molten zone of Kilauea Iki lava lake. The geothermometers developed here are also potentially applicable to glassy samples from other Kilauea lava lakes and to rapidly quenched lava samples from eruptions of Kilauea and Mauna Loa. ?? 1987 Springer-Verlag.

  16. Glutathione and glutaredoxin act as a backup of human thioredoxin reductase 1 to reduce thioredoxin 1 preventing cell death by aurothioglucose.

    PubMed

    Du, Yatao; Zhang, Huihui; Lu, Jun; Holmgren, Arne

    2012-11-01

    Thioredoxin reductase 1 (TrxR1) in cytosol is the only known reductant of oxidized thioredoxin 1 (Trx1) in vivo so far. We and others found that aurothioglucose (ATG), a well known active-site inhibitor of TrxR1, inhibited TrxR1 activity in HeLa cell cytosol but had no effect on the viability of the cells. Using a redox Western blot analysis, no change was observed in redox state of Trx1, which was mainly fully reduced with five sulfhydryl groups. In contrast, auranofin killed cells and oxidized Trx1, also targeting mitochondrial TrxR2 and Trx2. Combining ATG with ebselen gave a strong synergistic effect, leading to Trx1 oxidation, reactive oxygen species accumulation, and cell death. We hypothesized that there should exist a backup system to reduce Trx1 when only TrxR1 activity was lost. Our results showed that physiological concentrations of glutathione, NADPH, and glutathione reductase reduced Trx1 in vitro and that the reaction was strongly stimulated by glutaredoxin1. Simultaneous depletion of TrxR activity by ATG and glutathione by buthionine sulfoximine led to overoxidation of Trx1 and loss of HeLa cell viability. In conclusion, the glutaredoxin system and glutathione have a backup role to keep Trx1 reduced in cells with loss of TrxR1 activity. Monitoring the redox state of Trx1 shows that cell death occurs when Trx1 is oxidized, followed by general protein oxidation catalyzed by the disulfide form of thioredoxin.

  17. Structural insight into the type-II mitochondrial NADH dehydrogenases.

    PubMed

    Feng, Yue; Li, Wenfei; Li, Jian; Wang, Jiawei; Ge, Jingpeng; Xu, Duo; Liu, Yanjing; Wu, Kaiqi; Zeng, Qingyin; Wu, Jia-Wei; Tian, Changlin; Zhou, Bing; Yang, Maojun

    2012-11-15

    The single-component type-II NADH dehydrogenases (NDH-2s) serve as alternatives to the multisubunit respiratory complex I (type-I NADH dehydrogenase (NDH-1), also called NADH:ubiquinone oxidoreductase; EC 1.6.5.3) in catalysing electron transfer from NADH to ubiquinone in the mitochondrial respiratory chain. The yeast NDH-2 (Ndi1) oxidizes NADH on the matrix side and reduces ubiquinone to maintain mitochondrial NADH/NAD(+) homeostasis. Ndi1 is a potential therapeutic agent for human diseases caused by complex I defects, particularly Parkinson's disease, because its expression restores the mitochondrial activity in animals with complex I deficiency. NDH-2s in pathogenic microorganisms are viable targets for new antibiotics. Here we solve the crystal structures of Ndi1 in its substrate-free, NADH-, ubiquinone- and NADH-ubiquinone-bound states, to help understand the catalytic mechanism of NDH-2s. We find that Ndi1 homodimerization through its carboxy-terminal domain is critical for its catalytic activity and membrane targeting. The structures reveal two ubiquinone-binding sites (UQ(I) and UQ(II)) in Ndi1. NADH and UQ(I) can bind to Ndi1 simultaneously to form a substrate-protein complex. We propose that UQ(I) interacts with FAD to act as an intermediate for electron transfer, and that NADH transfers electrons through this FAD-UQ(I) complex to UQ(II). Together our data reveal the regulatory and catalytic mechanisms of Ndi1 and may facilitate the development or targeting of NDH-2s for potential therapeutic applications.

  18. Sulfidogenesis in low pH (3.8-4.2) media by a mixed population of acidophilic bacteria.

    PubMed

    Kimura, Sakurako; Hallberg, Kevin B; Johnson, D Barrie

    2006-03-01

    A defined mixed bacterial culture was established which catalyzed dissimilatory sulfate reduction, using glycerol as electron donor, at pH 3.8-4.2. The bacterial consortium comprised a endospore-forming sulfate reducing bacterium (isolate M1) that had been isolated from acidic sediment in a geothermal area of Montserrat (West Indies) and which had 94% sequence identity (of its 16S rRNA gene) to the Gram-positive neutrophile Desulfosporosinus orientis, and a Gram-negative (non sulfate-reducing) acidophile (isolate PFBC) that shared 99% gene identity with Acidocella aromatica. Whilst M1 was an obligate anaerobe, isolate PFBC, as other Acidocella spp., only grew in pure culture in aerobic media. Analysis of microbial communities, using a combination of total bacterial counts and fluorescent in situ hybridization, confirmed that concurrent growth of both bacteria occurred during sulfidogenesis under strictly anoxic conditions in a pH-controlled fermenter. In pure culture, M1 oxidized glycerol incompletely, producing stoichiometric amounts of acetic acid. In mixed culture with PFBC, however, acetic acid was present only in small concentrations and its occurrence was transient. Since M1 did not oxidize acetic acid, it was inferred that this metabolite was catabolized by Acidocella PFBC which, unlike glycerol, was shown to support the growth of this acidophile under aerobic conditions. In fermenter cultures maintained at pH 3.8-4.2, sulfidogenesis resulted in the removal of soluble zinc (as solid phase ZnS) whilst ferrous iron remained in solution. Potential syntrophic interactions, involving hydrogen transfer between M1 and PFBC, are discussed, as is the potential of sulfidogenesis in acidic liquors for the selective recovery of heavy metals from wastewaters. PMID:16456614

  19. Improved method for producing catalytic carbon and the potential for increasing its use in commercial applications

    USGS Publications Warehouse

    Kruse, C.W.; Lizzio, A.A.; DeBarr, J.A.; Feizoulof, C.A.

    1997-01-01

    This paper describes an improved method for producing a catalytic carbon, which was first produced in the late 1960s. The new activated carbon (AC) removes and destroys organic pollutants in aqueous solutions. To determine the effects of altering the pore structure and surface chemistry of activated carbons, carbons differing in the amount of functional groups on their surfaces were prepared in three steps: (1) oxidizing AC with boiling nitric acid, (2) washing oxidized AC with water to remove the acid, and (3) heating oxidized AC to temperatures beteween 100 and 925 ??C. The surfaces of the products were characterized by determining the amount of CO2 and CO evolved during temperature-programmed desorption. Depending on the desorption temperature, these modified carbons showed enhanced adsorptive and/or catalytic properties that included (1) carbon molecular sieves for separating oxygen from nitrogen, (2) increased capacity for adsorbing sulfur dioxide, (3) stronger adsorption of p-nitrophenol from water, and (4) catalysis of dehydrochlorination reactions. A dehydrohalogenation catalyst produced by the oxidation/ desorption steps was found to be similar to one prepared in the 1960s by oxidizing AC with air at 500-700 ??C. The dehydrohalogenation catalyst produced by either the old method or the new method involves an oxidized surface that has been exposed to a 500-700 ??C temperature range. This carbon catalyst retains modified adsorptive properties of the AC from which it is produced. It can be used both to adsorb pollutants from liquid or gaseous streams and to convert them to recyclable products.

  20. Patterns of ecological specialization among microbial populations in the Red Sea and diverse oligotrophic marine environments.

    PubMed

    Thompson, Luke R; Field, Chris; Romanuk, Tamara; Ngugi, David; Siam, Rania; El Dorry, Hamza; Stingl, Ulrich

    2013-06-01

    Large swaths of the nutrient-poor surface ocean are dominated numerically by cyanobacteria (Prochlorococcus), cyanobacterial viruses (cyanophage), and alphaproteobacteria (SAR11). How these groups thrive in the diverse physicochemical environments of different oceanic regions remains poorly understood. Comparative metagenomics can reveal adaptive responses linked to ecosystem-specific selective pressures. The Red Sea is well-suited for studying adaptation of pelagic-microbes, with salinities, temperatures, and light levels at the extreme end for the surface ocean, and low nutrient concentrations, yet no metagenomic studies have been done there. The Red Sea (high salinity, high light, low N and P) compares favorably with the Mediterranean Sea (high salinity, low P), Sargasso Sea (low P), and North Pacific Subtropical Gyre (high light, low N). We quantified the relative abundance of genetic functions among Prochlorococcus, cyanophage, and SAR11 from these four regions. Gene frequencies indicate selection for phosphorus acquisition (Mediterranean/Sargasso), DNA repair and high-light responses (Red Sea/Pacific Prochlorococcus), and osmolyte C1 oxidation (Red Sea/Mediterranean SAR11). The unexpected connection between salinity-dependent osmolyte production and SAR11 C1 metabolism represents a potentially major coevolutionary adaptation and biogeochemical flux. Among Prochlorococcus and cyanophage, genes enriched in specific environments had ecotype distributions similar to nonenriched genes, suggesting that inter-ecotype gene transfer is not a major source of environment-specific adaptation. Clustering of metagenomes using gene frequencies shows similarities in populations (Red Sea with Pacific, Mediterranean with Sargasso) that belie their geographic distances. Taken together, the genetic functions enriched in specific environments indicate competitive strategies for maintaining carrying capacity in the face of physical stressors and low nutrient availability. PMID

  1. Mode of action uncovered for the specific reduction of methane emissions from ruminants by the small molecule 3-nitrooxypropanol.

    PubMed

    Duin, Evert C; Wagner, Tristan; Shima, Seigo; Prakash, Divya; Cronin, Bryan; Yáñez-Ruiz, David R; Duval, Stephane; Rümbeli, Robert; Stemmler, René T; Thauer, Rudolf Kurt; Kindermann, Maik

    2016-05-31

    Ruminants, such as cows, sheep, and goats, predominantly ferment in their rumen plant material to acetate, propionate, butyrate, CO2, and methane. Whereas the short fatty acids are absorbed and metabolized by the animals, the greenhouse gas methane escapes via eructation and breathing of the animals into the atmosphere. Along with the methane, up to 12% of the gross energy content of the feedstock is lost. Therefore, our recent report has raised interest in 3-nitrooxypropanol (3-NOP), which when added to the feed of ruminants in milligram amounts persistently reduces enteric methane emissions from livestock without apparent negative side effects [Hristov AN, et al. (2015) Proc Natl Acad Sci USA 112(34):10663-10668]. We now show with the aid of in silico, in vitro, and in vivo experiments that 3-NOP specifically targets methyl-coenzyme M reductase (MCR). The nickel enzyme, which is only active when its Ni ion is in the +1 oxidation state, catalyzes the methane-forming step in the rumen fermentation. Molecular docking suggested that 3-NOP preferably binds into the active site of MCR in a pose that places its reducible nitrate group in electron transfer distance to Ni(I). With purified MCR, we found that 3-NOP indeed inactivates MCR at micromolar concentrations by oxidation of its active site Ni(I). Concomitantly, the nitrate ester is reduced to nitrite, which also inactivates MCR at micromolar concentrations by oxidation of Ni(I). Using pure cultures, 3-NOP is demonstrated to inhibit growth of methanogenic archaea at concentrations that do not affect the growth of nonmethanogenic bacteria in the rumen. PMID:27140643

  2. Decreased oxidative stress in prehepatic portal hypertensive rat livers following the induction of diabetes.

    PubMed

    Evelson, P; Llesuy, S; Filinger, E; Rodriguez, R R; Lemberg, A; Scorticati, C; Susemihl, M; Villareal, I; Polo, J M; Peredo, H; Perazzo, J C

    2004-03-01

    1. Oxidative stress (OS) is a biological entity indicated as being responsible for several pathologies, including diabetes. Diabetes can also be associated with human cirrhosis. Portal hypertension (PH), a major syndrome in cirrhosis, produces hyperdynamic splanchnic circulation and hyperaemia. The present study was designed to investigate the occurrence of OS in prehepatic PH rat livers following the induction of diabetes. 2. Five groups of rats were used: control, sham operated, chronic diabetes (induced with a single dose of streptozotocin at 60 mg/kg, i.p.), prehepatic PH and chronic diabetic plus prehepatic PH. The occurrence of OS was determined in liver homogenates by measuring hydroperoxide-initiated chemiluminescence and the activity of anti-oxidant enzymes (superoxide dismutase, catalase and glutathione peroxidase). 3. Prehepatic PH produced a significant increase in hydroperoxide-initiated chemiluminescence in the liver compared with control and sham-operated rats, whereas the liver in chronic diabetic rats showed no difference. However, chemiluminescence values decreased almost by 50% in the chronic diabetic plus prehepatic PH group. Concomitantly, the activities of the anti-oxidant enzymes in chronic diabetes, prehepatic PH and chronic diabetic plus prehepatic PH groups were decreased (P < 0.05 vs control and sham-operated groups). 4. Livers from the chronic diabetic group did not show any evidence of the occurrence of OS, whereas the prehepatic PH group showed the occurrence of OS. The association of PH and chronic diabetes resulted in a significant decrease in the occurrence of OS, which could be explained by an anti-oxidant response to an OS. PMID:15008960

  3. Effects of dietary selenium on tissue concentrations,pathology, oxidative stress, and immune function in common eiders (Somateria mollissima)

    USGS Publications Warehouse

    Franson, J. Christian; Hoffman, David; Wells-Berlin, Alicia M.; Perry, Matthew C.; Shearn-Bochsler, Valerie I.; Finley, Daniel L.; Flint, Paul L.; Hollmén, Tuula E.

    2007-01-01

    Common eiders (Somateria mollissima) were fed added Se (as L-selenomethionine) in concentrations increasing from 10 to 80 ppm in a pilot study (Study 1) or 20 (low exposure) and up to 60 (high exposure) ppm Se in Study 2. Body weights of Study 1 ducks and high-exposure ducks in Study 2 declined rapidly. Mean concentrations of Se in blood reached 32.4 ppm wet weight in Study 1 and 17.5 ppm wet weight in high-exposure birds in Study 2. Mean Se concentrations in liver ranged from 351 (low exposure, Study 2) to 1252 ppm dry weight (Study 1). Oxidative stress was evidenced by Se-associated effects on glutathione metabolism. As Se concentrations in liver increased, Se-dependent glutathione peroxidase activity, glutathione reductase activity, oxidized glutathione levels, and the ratio of hepatic oxidized to reduced glutathione increased. In Study 2, the T-cell-mediated immune response was adversely affected in high-exposure eiders, but ducks in the low-exposure group exhibited evidence of an enhanced antibody-mediated immune response. Gross lesions in high-exposure ducks included emaciation, absence of thymus, and loss of nails from digits. Histologic lesions included severe depletion of lymphoid organs, hepatopathy, and necrosis of feather pulp and feather epithelium. Field studies showed that apparently healthy sea ducks generally have higher levels of Se in liver than healthy fresh-water birds, but lower than concentrations found in our study. Data indicate that common eiders and probably other sea ducks possess a higher threshold, or adverse effect level, for Se in tissues than fresh-water species. However, common eiders developed signs of Se toxicity similar to those seen in fresh-water birds.

  4. Identification of one-electron reductases that activate both the hypoxia prodrug SN30000 and diagnostic probe EF5.

    PubMed

    Wang, Jingli; Guise, Chris P; Dachs, Gabi U; Phung, Yen; Hsu, Annie Huai-Ling; Lambie, Neil K; Patterson, Adam V; Wilson, William R

    2014-10-15

    SN30000 is a second-generation benzotriazine-N-oxide hypoxia-activated prodrug scheduled for clinical trial. Previously we showed that covalent binding of the hypoxia probe EF5 predicts metabolic activation of SN30000 in a panel of cancer cell lines under anoxia, suggesting that they are activated by the same reductases. However the identity of these reductases is unknown. Here, we test whether forced expression of nine oxidoreductases with known or suspected roles in bioreductive prodrug metabolism (AKR1C3, CYB5R3, FDXR, MTRR, NDOR1, NOS2A, NQO1, NQO2 and POR) enhances oxic or anoxic reduction of SN30000 and EF5 by HCT116 cells. Covalent binding of (14)C-EF5 and reduction of SN30000 to its 1-oxide and nor-oxide metabolites was highly selective for anoxia in all lines, with significantly elevated anoxic metabolism of both compounds in lines over-expressing POR, MTRR, NOS2A or NDOR1. There was a strong correlation between EF5 binding and SN30000 metabolism under anoxia across the cell lines (R(2)=0.84, p=0.0001). Antiproliferative potency of SN30000 under anoxia was increased most strongly by overexpression of MTRR and POR. Transcript abundance in human tumours, evaluated using public domain mRNA expression data, was highest for MTRR, followed by POR, NOS2A and NDOR1, with little variation between tumour types. Immunostaining of tissue microarrays demonstrated variable MTRR protein expression across 517 human cancers with most displaying low expression. In conclusion, we have identified four diflavin reductases (POR, MTRR, NOS2A and NDOR1) capable of reducing both SN30000 and EF5, further supporting use of 2-nitroimidazole probes to predict the ability of hypoxic cells to activate SN30000. PMID:25130546

  5. Met(104) is the CO-replaceable ligand at Fe(II) heme in the CO-sensing transcription factor BxRcoM-1.

    PubMed

    Bowman, Hannah E; Dent, Matthew R; Burstyn, Judith N

    2016-07-01

    Both Met(104) and Met(105) are involved, either directly or indirectly, in the redox mediated ligand switch of the heme-dependent transcription factor, RcoM-1. Recent studies of Burkholderia xenovorans RcoM identified Cys(94) as the thiolate ligand in the Fe(III) state of the heme cofactor. Upon reduction, a neutral donor replaces Cys(94) trans to His(74). Homology modelling implicated either Met(104) or Met(105) as the possible ligand in the Fe(II) state. We spectroscopically compared wild type (WT) RcoM-1 to three Met-to-Leu variants (M104L, M105L, and M104L/M105L) to identify which Met residue acts as the ligand. All proteins were isolated as admixtures of Fe(III) and Fe(II)-CO heme; oxidation by ferricyanide enables study of homogeneous oxidation and coordination states. Met(104) is the CO-replaceable Fe(II) heme ligand. The magnetic circular dichroism (MCD) spectrum of Fe(II) M105L resembled WT. M104L and M104L/M105L, however, showed spectra arising from the formation of a high-spin, five-coordinate species indicating the loss of the ligand. The electron paramagnetic resonance (EPR) spectra of WT Fe(III) RcoM-1, oxidized Fe(III) M104L, and as-isolated M105L exhibited narrow, rhombic low-spin signals typical of thiolate-bound hemes. In contrast, oxidized Fe(III) M105L and oxidized Fe(III) M104L/M105L revealed a broad, rhombic low-spin, six-coordinate signal indicative of replacement of the thiolate by a neutral ligand. Thus, we conclude that Met(105) is important to the stability of the Fe(III) heme pocket during oxidation. PMID:27283195

  6. Chemical reactions on solid surfaces: Atomistic observations by scanning tunneling microscopy

    NASA Astrophysics Data System (ADS)

    Madix, R. J.; Crew, W. W.; Guo, X.-C.

    1997-04-01

    A scanning tunneling microscope has been developed which allows manipulation and control of the surface as well as scanning tunneling microscopy without transfer of the crystal off the manipulator to the microscope. The microscope is of the 'Johnnie Walker' type and is lowered onto the crystal, which is itself housed in a versatile transfer carriage. In this fashion surfaces can be ion bombarded, chemically treated, etc. and examined by the microscope at temperatures ranging from 120-400 K with atomic resolution without change in surface temperature. With this microscope we have studied the reaction of carbon monoxide with oxygen on Cu(110). At an ambient pressure of 10 -4 Torr carbon monoxide reacts with the p(2 × 1) islands of oxygen at a measurable rate only at 400 K or above. Reaction is approximately 1000 times faster along the (001) direction of the oxide islands than along the (110) direction. Reaction does not occur internal to the island unless there are defects to initiate the reaction. At 400 K the oxide islands do not maintain an equilibrium shape or distribution when reacting with ambient carbon monoxide, though in the presence of a low pressure of oxygen they appear to do so. At 150 K the p(2 × 1) oxide islands are inert to reaction with carbon monoxide and, additionally, short CuO chains are also unreactive. Reaction between pre-adsorbed carbon monoxide and ambient oxygen is observed, implying that mobile oxygen atoms which have not yet formed surface-bound pseudomolecules, can react with adsorbed carbon monoxide.

  7. Characteristics and applications of UV/controlled-release H2O2 for urban runoff treatment

    NASA Astrophysics Data System (ADS)

    Sun, S.; Lee, E.; Schwartz, F. W.; Kim, Y.

    2010-12-01

    Nonpoint source (NPS) pollution for urban runoff has been considered as one of the leading causes of receiving water degradation. Among the NPS pollutants, petroleum hydrocarbons, such as BTEX; polynuclear aromatic hydrocarbons (PAHs) and gasoline additives (such as MTBE) are gaining more attention due to their resistance to biodegradation, high detention frequency and toxicity. Opportunities exist for the development of in situ scheme to remediate organic pollutants in urban runoff. The Ultraviolet (UV)/H2O2 process uses direct photolysis of H2O2 under UV irradiation, producing hydroxyl radicals. They attack organic compounds relatively non-selectively with rate constants ranging from 106 to 1010 M-1s-1, oxidizing them by addition to double bonds or hydrogen atom abstraction. This study aims to develop a controlled-release system (CRS) that can deliver H2O2 at a rate which is predetermined by the design of the system and nearly independent of environmental conditions. A series of correlation analyses and literature review suggested that UV/CRS-H2O2 system can provide an efficient scheme for treating organic pollutants in urban runoff in situ. CRS-H2O2 forms were manufactured by dispersing fine sodium percarbonate (Na2CO3`1.5H2O2) granules, which can rapidly release H2O2 when dissolved in water, in liquid wax matrix. Release rates of these CRS forms were measured using column experiments and computer modeling. These column and numerical simulation data indicated the CRP could deliver H2O2 in a controlled concentration, which is efficient to treat organic pollution in urban runoff for several years. This type of new approach may be suitable for in situ remediation of urban storm runoff in which low to medium-concentration contaminants exist

  8. Peroxynitrite and hydrogen peroxide elicit similar cellular stress responses mediated by the Ccp1 sensor protein.

    PubMed

    Martins, Dorival; Bakas, Iolie; McIntosh, Kelly; English, Ann M

    2015-08-01

    Peroxynitrite [ONOO(H)] is an oxidant associated with deleterious effects in cells. Because it is an inorganic peroxide that reacts rapidly with peroxidases, we speculated that cells may respond to ONOO(H) and H2O2 challenge in a similar manner. We exposed yeast cells to SIN-1, a well-characterized ONOO(H) generator, and observed stimulation of catalase and peroxiredoxin (Prx) activities. Previously, we reported that H2O2 challenge increases these activities in wild-type cells and in cells producing the hyperactive mutant H2O2 sensor Ccp1(W191F) but not in Ccp1-knockout cells (ccp1Δ). We find here that the response of ccp1Δ and ccp1(W191F) cells to SIN-1 mirrors that to H2O2, identifying Ccp1 as a sensor of both peroxides. SIN-1 simultaneously releases (•)NO and O2(•-), which react to form ONOO(H), but exposure of the three strains separately to an (•)NO donor (spermine-NONOate) or an O2(•-) generator (paraquat) mainly depresses catalase or Prx activity, whereas co-challenge with the NONOate and paraquat stimulates these activities. Because Ccp1 appears to sense ONOO(H) in cells, we examined its reaction with ONOO(H) in vitro and found that peroxynitrous acid (ONOOH) rapidly (k2>10(6)M(-1)s(-1)) oxidizes purified Ccp1 to an intermediate with spectral and ferrocytochrome-oxidizing properties indistinguishable from those of its well-characterized compound I formed with H2O2. Importantly, the nitrite released from ONOOH is not oxidized to (•)NO2 by Ccp1(׳)s compound I, unlike peroxidases involved in immune defense. Overall, our results reveal that yeast cells mount a common antioxidant response to ONOO(H) and H2O2, with Ccp1 playing a pivotal role as an inorganic peroxide sensor.

  9. Copper, zinc superoxide dismutase catalyzes hydroxyl radical production from hydrogen peroxide.

    PubMed

    Yim, M B; Chock, P B; Stadtman, E R

    1990-07-01

    Cu,Zn superoxide dismutase (Cu,Zn-SOD; EC 1.15.1.1) is known to be inhibited slowly by H2O2. Using EPR and the spin traps 5,5-dimethyl-1-pyrroline 1-oxide (DMPO) and N-tert-butyl-alpha-phenylnitrone (PBN), we have shown that Cu,Zn-SOD catalyzes the formation of "free" .OH radicals from H2O2 in pH 7.6 bicarbonate buffer. Supporting evidence includes the following: (i) H2O2 and active Cu,Zn-SOD are required to yield significant signals from spin-trap-OH adducts. (ii) With O2-., Cu,Zn-SOD causes the appearance of intense resonance signals due to DMPO-OH adducts. These signals were inhibited strongly by catalase. (iii) With H2O2, Cu,Zn-SOD, and DMPO, radical scavengers formate and azide, but not ethanol, decrease DMPO-OH signals while causing new intense signals due to their corresponding DMPO-radical adducts. Failure of ethanol to quench DMPO-OH signals is discussed in light of the positively charged active channel of the enzyme. (iv) With PBN as a spin trap, ethanol quenches .OH radical signals and yields PBN-trapped hydroxyethyl radical signals. (v) Mn-SOD does not catalyze "free" .OH radical formation and it also exerts no effect on the signals of DMPO-OH adducts when added together with the Cu,Zn-SOD. The capacity of Cu,Zn-SOD to generate "free" .OH radicals from H2O2 may in part explain the biological damage associated with elevated intracellular SOD activity. PMID:2164216

  10. ChlR Protein of Synechococcus sp. PCC 7002 Is a Transcription Activator That Uses an Oxygen-sensitive [4Fe-4S] Cluster to Control Genes involved in Pigment Biosynthesis*

    PubMed Central

    Ludwig, Marcus; Pandelia, Maria-Eirini; Chew, Chyue Yie; Zhang, Bo; Golbeck, John H.; Krebs, Carsten; Bryant, Donald A.

    2014-01-01

    Synechococcus sp. PCC 7002 and many other cyanobacteria have two genes that encode key enzymes involved in chlorophyll a, biliverdin, and heme biosynthesis: acsFI/acsFII, ho1/ho2, and hemF/hemN. Under atmospheric O2 levels, AcsFI synthesizes 3,8-divinyl protochlorophyllide from Mg-protoporphyrin IX monomethyl ester, Ho1 oxidatively cleaves heme to form biliverdin, and HemF oxidizes coproporphyrinogen III to protoporphyrinogen IX. Under microoxic conditions, another set of genes directs the synthesis of alternative enzymes AcsFII, Ho2, and HemN. In Synechococcus sp. PCC 7002, open reading frame SynPCC7002_A1993 encodes a MarR family transcriptional regulator, which is located immediately upstream from the operon comprising acsFII, ho2, hemN, and desF (the latter encodes a putative fatty acid desaturase). Deletion and complementation analyses showed that this gene, denoted chlR, is a transcriptional activator that is essential for transcription of the acsFII-ho2-hemN-desF operon under microoxic conditions. Global transcriptome analyses showed that ChlR controls the expression of only these four genes. Co-expression of chlR with a yfp reporter gene under the control of the acsFII promoter from Synechocystis sp. PCC 6803 in Escherichia coli demonstrated that no other cyanobacterium-specific components are required for proper functioning of this regulatory circuit. A combination of analytical methods and Mössbauer and EPR spectroscopies showed that reconstituted, recombinant ChlR forms homodimers that harbor one oxygen-sensitive [4Fe-4S] cluster. We conclude that ChlR is a transcriptional activator that uses a [4Fe-4S] cluster to sense O2 levels and thereby control the expression of the acsFII-ho2-hemN-desF operon. PMID:24782315

  11. Graphite Oxidation Simulation in HTR Accident Conditions

    SciTech Connect

    El-Genk, Mohamed

    2012-10-19

    Massive air and water ingress, following a pipe break or leak in steam-generator tubes, is a design-basis accident for high-temperature reactors (HTRs). Analysis of these accidents in both prismatic and pebble bed HTRs requires state-of-the-art capability for predictions of: 1) oxidation kinetics, 2) air helium gas mixture stratification and diffusion into the core following the depressurization, 3) transport of multi-species gas mixture, and 4) graphite corrosion. This project will develop a multi-dimensional, comprehensive oxidation kinetics model of graphite in HTRs, with diverse capabilities for handling different flow regimes. The chemical kinetics/multi-species transport model for graphite burning and oxidation will account for temperature-related changes in the properties of graphite, oxidants (O2, H2O, CO), reaction products (CO, CO2, H2, CH4) and other gases in the mixture (He and N2). The model will treat the oxidation and corrosion of graphite in geometries representative of HTR core component at temperatures of 900°C or higher. The developed chemical reaction kinetics model will be user-friendly for coupling to full core analysis codes such as MELCOR and RELAP, as well as computational fluid dynamics (CFD) codes such as CD-adapco. The research team will solve governing equations for the multi-dimensional flow and the chemical reactions and kinetics using Simulink, an extension of the MATLAB solver, and will validate and benchmark the model's predictions using reported experimental data. Researchers will develop an interface to couple the validated model to a commercially available CFD fluid flow and thermal-hydraulic model of the reactor , and will perform a simulation of a pipe break in a prismatic core HTR, with the potential for future application to a pebble-bed type HTR.

  12. Differential oxidant tolerance determined by the key transcription factor Yap1 is controlled by levels of the Yap1-binding protein, Ybp1.

    PubMed

    Gulshan, Kailash; Lee, Stella S; Moye-Rowley, W Scott

    2011-09-30

    The Saccharomyces cerevisiae transcription factor Yap1 is a central determinant of oxidative stress tolerance. This protein is found primarily in the cytoplasm in the absence of oxidative stress but, upon exposure to oxidants, rapidly translocates to the nucleus and activates expression of target genes. Although both diamide and H(2)O(2) have been used to impose oxidative stress on cells, these different oxidants trigger Yap1 nuclear localization in distinctly different ways. Diamide appears to oxidize particular cysteine residues on Yap1, leading to inhibition of association of Yap1 with the nuclear exportin Crm1. Crm1 would normally transport Yap1 out of the nucleus. H(2)O(2) activation of Yap1 nuclear localization requires the participation of the glutathione peroxidase Gpx3 and the Yap1-binding protein Ybp1. H(2)O(2) exposure triggers formation of a dual disulfide bonded Yap1 that is catalyzed by the presence of Gpx3 and Ybp1. In the current study, we have determined that two distinct pools of Yap1 exist in the cell. These pools are designated by the level of Ybp1. Ybp1 interacts directly with Yap1 and these proteins form a stable complex in vivo. Genetic and biochemical experiments indicate that Ybp1 is rate-limiting for Yap1 oxidative folding during H(2)O(2) stress. The fungal pathogen Candida glabrata expresses a protein homologous to Ybp1 called CgYbp1. Overproduction of CgYbp1 elevated H(2)O(2) tolerance in this pathogen indicating that the determinative role of Ybp1 in setting the level of H(2)O(2) resistance has been evolutionarily conserved. PMID:21844193

  13. Gender differences in cancer susceptibility: role of oxidative stress.

    PubMed

    Ali, Imran; Högberg, Johan; Hsieh, Jui-Hua; Auerbach, Scott; Korhonen, Anna; Stenius, Ulla; Silins, Ilona

    2016-10-01

    Cancer is a leading cause of death worldwide and environmental factors, including chemicals, have been suggested as major etiological incitements. Cancer statistics indicates that men get more cancer than women. However, differences in the known risk factors including life style or occupational exposure only offer partial explanation. Using a text mining tool, we have investigated the scientific literature concerning male- and female-specific rat carcinogens that induced tumors only in one gender in NTP 2-year cancer bioassay. Our evaluation shows that oxidative stress, although frequently reported for both male- and female-specific rat carcinogens, was mentioned significantly more in literature concerning male-specific rat carcinogens. Literature analysis of testosterone and estradiol showed the same pattern. Tox21 high-throughput assay results, although showing only weak association of oxidative stress-related processes for male- and female-specific rat carcinogens, provide additional support. We also analyzed the literature concerning 26 established human carcinogens (IARC group 1). Oxidative stress was more frequently reported for the majority of these carcinogens, and the Tox21 data resembled that of male-specific rat carcinogens. Thus, our data, based on about 600000 scientific abstracts and Tox21 screening assays, suggest a link between male-specific carcinogens, testosterone and oxidative stress. This implies that a different cellular response to oxidative stress in men and women may be a critical factor in explaining the greater cancer susceptibility observed in men. Although the IARC carcinogens are classified as human carcinogens, their classification largely based on epidemiological evidence from male cohorts, which raises the question whether carcinogen classifications should be gender specific. PMID:27481070

  14. CYP4F2 Is a Vitamin K1 Oxidase: An Explanation for Altered Warfarin Dose in Carriers of the V433M Variant

    PubMed Central

    McDonald, Matthew G.; Rieder, Mark J.; Nakano, Mariko; Hsia, Clara K.; Rettie, Allan E.

    2009-01-01

    Genetic polymorphisms in VKORC1 and CYP2C9, genes controlling vitamin K1 (VK1) epoxide reduction and (S)-warfarin metabolism, respectively, are major contributors to interindividual variability in warfarin dose. The V433M polymorphism (rs2108622) in CYP4F2 has also been associated with warfarin dose and speculatively linked to altered VK1 metabolism. Therefore, the purpose of the present study was to determine the role of CYP4F2 and the V433M polymorphism in the metabolism of VK1 by human liver. In vitro metabolic experiments with accompanying liquid chromatography-tandem mass spectrometry analysis demonstrated that recombinant CYP4F2 (Supersomes) and human liver microsomes supplemented with NADPH converted VK1 to a single product. A screen of all commercially available P450 Supersomes showed that only CYP4F2 was capable of metabolizing VK1 to this product. Steady-state kinetic analysis with recombinant CYP4F2 and with human liver microsomes revealed a substrate Km of 8 to 10 μM. Moreover, anti-CYP4F2 IgG, as well as several CYP4F2-selective chemical inhibitors, substantially attenuated the microsomal reaction. Finally, human liver microsomes genotyped for rs2108622 demonstrated reduced vitamin K1 oxidation and lower CYP4F2 protein concentrations in carriers of the 433M minor allele. These data demonstrate that CYP4F2 is a vitamin K1 oxidase and that carriers of the CYP4F2 V433M allele have a reduced capacity to metabolize VK1, secondary to an rs2108622-dependent decrease in steady-state hepatic concentrations of the enzyme. Therefore, patients with the rs2108622 polymorphism are likely to have elevated hepatic levels of VK1, necessitating a higher warfarin dose to elicit the same anticoagulant response. PMID:19297519

  15. Effects of ocean acidification on the swimming ability, development and biochemical responses of sand smelt larvae.

    PubMed

    Silva, Cátia S E; Novais, Sara C; Lemos, Marco F L; Mendes, Susana; Oliveira, Ana P; Gonçalves, Emanuel J; Faria, Ana M

    2016-09-01

    Ocean acidification, recognized as a major threat to marine ecosystems, has developed into one of the fastest growing fields of research in marine sciences. Several studies on fish larval stages point to abnormal behaviours, malformations and increased mortality rates as a result of exposure to increased levels of CO2. However, other studies fail to recognize any consequence, suggesting species-specific sensitivity to increased levels of CO2, highlighting the need of further research. In this study we investigated the effects of exposure to elevated pCO2 on behaviour, development, oxidative stress and energy metabolism of sand smelt larvae, Atherina presbyter. Larvae were caught at Arrábida Marine Park (Portugal) and exposed to different pCO2 levels (control: ~600μatm, pH=8.03; medium: ~1000μatm, pH=7.85; high: ~1800μatm, pH=7.64) up to 15days, after which critical swimming speed (Ucrit), morphometric traits and biochemical biomarkers were determined. Measured biomarkers were related with: 1) oxidative stress - superoxide dismutase and catalase enzyme activities, levels of lipid peroxidation and DNA damage, and levels of superoxide anion production; 2) energy metabolism - total carbohydrate levels, electron transport system activity, lactate dehydrogenase and isocitrate dehydrogenase enzyme activities. Swimming speed was not affected by treatment, but exposure to increasing levels of pCO2 leads to higher energetic costs and morphometric changes, with larger larvae in high pCO2 treatment and smaller larvae in medium pCO2 treatment. The efficient antioxidant response capacity and increase in energetic metabolism only registered at the medium pCO2 treatment may indicate that at higher pCO2 levels the capacity of larvae to restore their internal balance can be impaired. Our findings illustrate the need of using multiple approaches to explore the consequences of future pCO2 levels on organisms. PMID:27135570

  16. Key players of singlet oxygen-induced cell death in plants.

    PubMed

    Laloi, Christophe; Havaux, Michel

    2015-01-01

    The production of reactive oxygen species (ROS) is an unavoidable consequence of oxygenic photosynthesis. Singlet oxygen ((1)O2) is a highly reactive species to which has been attributed a major destructive role during the execution of ROS-induced cell death in photosynthetic tissues exposed to excess light. The study of the specific biological activity of (1)O2 in plants has been hindered by its high reactivity and short lifetime, the concurrent production of other ROS under photooxidative stress, and limited in vivo detection methods. However, during the last 15 years, the isolation and characterization of two (1)O2-overproducing mutants in Arabidopsis thaliana, flu and ch1, has allowed the identification of genetically controlled (1)O2 cell death pathways and a (1)O2 acclimation pathway that are triggered at sub-cytotoxic concentrations of (1)O2. The study of flu has revealed the control of cell death by the plastid proteins EXECUTER (EX)1 and EX2. In ch1, oxidized derivatives of β-carotene, such as β-cyclocitral and dihydroactinidiolide, have been identified as important upstream messengers in the (1)O2 signaling pathway that leads to stress acclimation. In both the flu and ch1 mutants, phytohormones act as important promoters or inhibitors of cell death. In particular, jasmonate has emerged as a key player in the decision between acclimation and cell death in response to (1)O2. Although the flu and ch1 mutants show many similarities, especially regarding their gene expression profiles, key differences, such as EXECUTER-independent cell death in ch1, have also been observed and will need further investigation to be fully understood. PMID:25699067

  17. Gender differences in cancer susceptibility: role of oxidative stress.

    PubMed

    Ali, Imran; Högberg, Johan; Hsieh, Jui-Hua; Auerbach, Scott; Korhonen, Anna; Stenius, Ulla; Silins, Ilona

    2016-10-01

    Cancer is a leading cause of death worldwide and environmental factors, including chemicals, have been suggested as major etiological incitements. Cancer statistics indicates that men get more cancer than women. However, differences in the known risk factors including life style or occupational exposure only offer partial explanation. Using a text mining tool, we have investigated the scientific literature concerning male- and female-specific rat carcinogens that induced tumors only in one gender in NTP 2-year cancer bioassay. Our evaluation shows that oxidative stress, although frequently reported for both male- and female-specific rat carcinogens, was mentioned significantly more in literature concerning male-specific rat carcinogens. Literature analysis of testosterone and estradiol showed the same pattern. Tox21 high-throughput assay results, although showing only weak association of oxidative stress-related processes for male- and female-specific rat carcinogens, provide additional support. We also analyzed the literature concerning 26 established human carcinogens (IARC group 1). Oxidative stress was more frequently reported for the majority of these carcinogens, and the Tox21 data resembled that of male-specific rat carcinogens. Thus, our data, based on about 600000 scientific abstracts and Tox21 screening assays, suggest a link between male-specific carcinogens, testosterone and oxidative stress. This implies that a different cellular response to oxidative stress in men and women may be a critical factor in explaining the greater cancer susceptibility observed in men. Although the IARC carcinogens are classified as human carcinogens, their classification largely based on epidemiological evidence from male cohorts, which raises the question whether carcinogen classifications should be gender specific.

  18. The use of tomato aminoaldehyde dehydrogenase 1 for the detection of aldehydes in fruit distillates.

    PubMed

    Frömmel, Jan; Tarkowski, Petr; Kopečný, David; Šebela, Marek

    2016-09-25

    Plant NAD(+)-dependent aminoaldehyde dehydrogenases (AMADHs, EC 1.2.1.19) belong to the family 10 of aldehyde dehydrogenases. They participate in the metabolism of polyamines or osmoprotectants. The enzymes are characterized by their broad substrate specificity covering ω-aminoaldehydes, aliphatic and aromatic aldehydes as well as nitrogen-containing heterocyclic aldehydes. The isoenzyme 1 from tomato (Solanum lycopersicum; SlAMADH1) oxidizes aliphatic aldehydes very efficiently and converts also furfural, its derivatives or benzaldehyde, which are present at low concentrations in alcoholic distillates such as fruit brandy. In this work, SlAMADH1 was examined as a bioanalytical tool for their detection. These aldehydes arise from fermentation processes or thermal degradation of sugars and their presence is related to health complications after consumption including nausea, emesis, sweating, decrease in blood pressure, hangover headache, among others. Sixteen samples of slivovitz (plum brandy) from local producers in Moravia, Czech Republic, were analyzed for their aldehyde content using a spectrophotometric activity assay with SlAMADH1. In all cases, there were oxidative responses observed when monitoring NADH production in the enzymatic reaction. Aldehydes in the distillate samples were also subjected to a standard determination using reversed-phase HPLC with spectrophotometric and tandem mass spectrometric detection after a derivatization with 2,4-dinitrophenylhydrazine. Results obtained by both methods were found to correlate well for a majority of the analyzed samples. The possible applicability of SlAMADH1 for the evaluation of aldehyde content in food and beverages has now been demonstrated. PMID:26703808

  19. Aliskiren Inhibits Neointimal Matrix Metalloproteinases in Experimental Atherosclerosis

    PubMed Central

    Wu, Tao-Cheng; Lee, Chiu-Yang; Lin, Shing-Jong; Chen, Jaw-Wen

    2016-01-01

    Background The renin-angiotensin system (RAS) plays an important role in atherosclerosis. Acting via the angiotensin II receptor, type 1, oxidative stress increases and contributes to endothelial dysfunction and vascular inflammation. Renin exerts effects through a renin receptor causing an increase in the efficiency of angiotensinogen cleavage and facilitates angiotensin II (Ang II) generation and action on cell surfaces. Ang II enhances proliferation and migration of vascular smooth muscle cells, indicating a direct involvement of the RAS in smooth muscle cell proliferation during neointimal formation. Aliskiren, a direct renin inhibitor, is a new oral antihypertensive drug. However, the role of the direct renin inhibitor in neointimal formation and vascular matrix metalloproteinases remains unclear. Methods To investigate the effects of aliskiren on the expression of vascular matrix metalloproteinases, we evaluated the aortic neointimal formation of high-cholesterol-fed animals after vascular injury in vivo and the cellular function of the tumor necrosis factor-α stimulated human aortic smooth muscle cells in vitro. Thereafter, we evaluated vascular expression (by western blot), activity (by gelatin zymography) and molecular pathway. Results In this study we demonstrated that aliskiren reduced neointimal hyperplasia in hypercholesterolemic rabbits after vascular injury and the expression of matrix metalloproteinases in the neointima. Aliskiren also inhibited the expression and activities of matrix metalloproteinases on tumor necrosis factor-α (TNF-α)-stimulated human aortic smooth muscle cells via the mitogen-activated protein kinase pathway. Conclusions The present study showed that aliskiren inhibited the expression of vascular matrix metalloproteinases. With these results, we have better clarified the potential role of renin inhibitors in human atherosclerosis. PMID:27713608

  20. Investigating students' understandings of the symbolic, macroscopic, and particulate domains of oxidation-reduction and the development of the redox concept inventory

    NASA Astrophysics Data System (ADS)

    Brandriet, Alexandra R.

    Previous literature regarding students' understandings about oxidation-reduction reactions has focused primarily on students' understandings at the symbolic domain, while literature regarding students' understandings about electrochemical cells has focused primarily on the particulate domain. This study attempts to explore the gap in the literature between students' symbolic oxidation-reduction understandings and particulate electrochemistry understandings by investigating students' understandings of multiple representations of oxidation-reduction reactions using sequential exploratory mixed-methods study. In the first phase of this study, students' misconceptions about oxidation-reduction at the symbolic, macroscopic, and particulate domains were elicited through qualitative research methods, and the results of this phase were used to create a concept inventory to measure students' understandings on a large scale in a quick and efficient manner. Six major misconceptions themes emerged during the students' interviews including 1) oxidation numbers, 2) surface features of the chemical representations, 3) electron transfer processes, 4) the role of the spectator ion, 5) the particulate and dynamic reaction process, and 6) charges & bonding. Using these themes, the Redox Concept Inventory (ROXCI) was developed and each item response choice was created based upon students' responses from the interviews. Therefore, the ROXCI is inherently designed to measure students' understandings. The ROXCI went through several rounds of revisions and evidence for the content validity, response process validity, test-criterion validity, internal consistency, and test-retest reliability are presented. The ROXCI was answered by more than 2000 students throughout the course of this study, and in the final round of implementations, the ROXCI was administered to over 1000 students in a national study. While previous studies have identified students' oxidation-reduction misconceptions in

  1. Identification and biochemical characterization of polyamine oxidases in amphioxus: Implications for emergence of vertebrate-specific spermine and acetylpolyamine oxidases.

    PubMed

    Wang, Huihui; Liu, Baobao; Li, Hongyan; Zhang, Shicui

    2016-01-10

    Polyamine oxidases (PAOs) have been identified in a wide variety of animals, as well as in fungi and plant. Generally, plant PAOs oxidize spermine (Spm), spermidine (Spd) and their acetylated derivatives, N(1)-acetylspermine (N(1)-Aspm) and N(1)-acetylspermidine (N(1)-Aspd), while yeast PAOs oxidize Spm, N(1)-Aspm and N(1)-Aspd, but not Spd. By contrast, two different enzymes, namely spermine oxidase (SMO) and acetylpolyamine oxidase (APAO), specifically catalyze the oxidation of Spm and N(1)-Aspm/N(1)-Aspd, respectively. However, our knowledge on the biochemical and structural characterization of PAOs remains rather limited, and their evolutionary history is still enigmatic. In this study, two amphioxus (Branchiostoma japonicum) PAO genes, named Bjpao1 and Bjpao2, were cloned and characterized. Both Bjpao1 and Bjpao2 displayed distinct tissue-specific expression patterns. Notably, rBjPAO1 oxidized both spermine and spermidine, but not N(1)-acetylspermine, whereas rBjPAO2 oxidizes both spermidine and N(1)-acetylspermine, but not spermine. To understand structure-function relationship, the enzymatic activities of mutant BjPAOs that were generated by site-directed mutagenesis and expressed in E. coli were examined, The results indicate that the residues H64, K301 and T460 in rBjPAO1, and H69, K315 and T467 in rBjPAO2 were all involved in substrate binding and enzyme catalytic activity to some extent. Based on our results and those of others, a model depicting the divergent evolution and functional specialization of vertebrate SMO and APAO genes is proposed. PMID:26367330

  2. Reactions of important OVOCs with hydrogen peroxide and ozone in the tropospheric aqueous phase

    NASA Astrophysics Data System (ADS)

    Schöne, Luisa; Weller, Christian; Herrmann, Hartmut

    2013-04-01

    Besides research on the microphysics of cloud droplets and similar aqueous systems in the troposphere, the chemistry of volatile organic compounds (VOCs) from anthropogenic and biogenic sources cannot be neglected for the understanding of tropospheric processes such as the organic particle mass formation. Emissions of biogenic volatile organic compounds (BVOCs) can exceed those of VOCs from anthropogenic sources by a factor of 10[1]. Oxidation products of BVOCs like glyoxal, methylglyoxal, glycolate, glyoxylate and pyruvate, glycolaldehyde, and the unsaturated compounds methacrolein and methyl vinyl ketone are known precursors for less volatile organic substances found in secondary organic aerosols[2,3]. Yet, the main decomposition of these substances is believed to occur via radical reactions. However, Tilgner and Herrmann[2] showed evidence that the turnovers by non-radical reactions with H2O2 or ozone and some non-oxidative organic accretion reactions may even exceed those from the most reactive species in the lower troposphere, the hydroxyl radical OH. This work investigated the reactivities of the atmospheric relevant oxidation products including pyruvic acid and glyoxylic acid towards O3 and H2O2 in the aqueous phase. Furthermore, pH effects were studied by measuring the kinetics of both the protonated and deprotonated forms. The measurements were performed using a UV/VIS-spectrometer (conventional and in addition a Stopped Flow technique) and capillary electrophoresis. In some cases the results indicate higher turnovers of H2O2 and ozone reactions compared to interactions with atmospheric radicals. The experimental data obtained will be presented and their implications for atmospheric multiphase chemistry are discussed. [1] Guenther et al., 1995, Journal of Geophysical Research - Atmosphere, 100(D5), 8873-8892. [2] Tilgner and Herrmann, 2010, Atmospheric Environment, 44, 5415-5422. [3] van Pinxteren et al., 2005, Atmospheric Environment, 39, 4305-4320.

  3. Activation of ROS/NF-{kappa}B and Ca{sup 2+}/CaM kinase II are necessary for VCAM-1 induction in IL-1{beta}-treated human tracheal smooth muscle cells

    SciTech Connect

    Luo, S.-F.; Chang, C.-C.; Lee, I-T.; Lee, C.-W.; Lin, W.-N.; Lin, C.-C.; Yang, C.-M.

    2009-05-15

    Histone acetylation regulated by histone acetyltransferases (HATs) and histone deacetylases (HDACs) plays a critical role in the expression of inflammatory genes, such as vascular cell adhesion molecule-1 (VCAM-1). Oxidative processes have been shown to induce VCAM-1 expression. Here, we investigated the mechanisms underlying IL-1{beta}-induced VCAM-1 expression in human tracheal smooth muscle cells (HTSMCs). Our results showed that IL-1{beta} enhanced HTSMCs-monocyte adhesion through up-regulation of VCAM-1, which was inhibited by pretreatment with selective inhibitors of PKC{alpha} (Goe6976), c-Src (PP1), NADPH oxidase [diphenylene iodonium (DPI) and apocynin (APO)], intracellular calcium chelator (BAPTA/AM), PI-PLC (U73122), CaM (calmidazolium chloride), CaM kinase II (KN62), p300 (garcinol), NF-{kappa}B (Bay11-7082), HDAC (trichostatin A), and ROS scavenger [N-acetyl-L-cysteine (NAC)] or transfection with siRNAs of MyD88, PKC{alpha}, Src, p47{sup phox}, p300, and HDAC4. Moreover, IL-1{beta} stimulated NF-{kappa}B and CaMKII phosphorylation through MyD88-dependent PI-PLC/PKC{alpha}/c-Src/ROS and PI-PLC/Ca{sup 2+}/CaM pathways, respectively. Activation of NF-{kappa}B and CaMKII may eventually lead to the acetylation of histone residues and phosphorylation of histone deacetylases. These findings suggested that IL-1{beta} induced VCAM-1 expression via these multiple signaling pathways in HTSMCs. Blockade of these pathways may reduce monocyte adhesion via VCAM-1 suppression and attenuation of the inflammatory responses in airway diseases.

  4. Metabolism and Disposition of Pacritinib (SB1518), an Orally Active Janus Kinase 2 Inhibitor in Preclinical Species and Humans.

    PubMed

    Jayaraman, Ramesh; Pasha, Mohammed Khalid; Williams, Anthony; Goh, Kee Cee; Ethirajulu, Kantharaj

    2015-01-01

    The ADME of Pacritinib (SB1518), an orally active JAK 2 inhibitor, was investigated in vitro and in vivo in preclinical species and humans. Pacritinib showed ~5 fold higher affinity to human plasma proteins relative to mouse in vitro. It was metabolized by human CYP3A4 in vitro, and did not significantly induce CYP3A and 1A2 in human hepatocytes. In vitro metabolism studies with mouse and human liver microsomes showed the presence of four major metabolites of Pacritinib -M1 (oxidation), M2 (dealkylation), M3 (oxidation), M4 (reduction). The in vitro and in vivo metabolic patterns observed in mice and humans were in good agreement. Qualitatively and quantitatively, none of the metabolites formed in vivo was >10% of Pacritinib in mouse, dog and humans. Pacritinib showed systemic clearance of 8.0, 1.6, 1.6 l/h/kg, volume of distribution of 14.2, 7.9, 8.5 l/kg, t1/2 of 5.6, 6.0, 4.6 h, and oral bioavailability of 39, 10, and 24% in mouse, rat and dog, respectively. In radiolabeled mass balance and QWBA studies in mice, ~91% of the dose was recovered in feces, suggesting biliary clearance, and maximum radioactivity was seen in the gastrointestinal tract followed by the kidney, heart and low activity in the brain. The relatively high exposures of Pacritinib in humans might be attributed to its very high plasma protein binding, low metabolic and/or biliary clearance.

  5. In Inclusion-Body Myositis Muscle Fibers Parkinson-Associated DJ-1 is Increased and Oxidized

    PubMed Central

    Terracciano, Chiara; Nogalska, Anna; Engel, W. King; Wojcik, Slawomir; Askanas, Valerie

    2008-01-01

    Sporadic inclusion-body myositis (s-IBM) is the most common muscle disease of older persons. The muscle-fiber molecular phenotype exhibits similarities to both Alzheimer-disease (AD) and Parkinson-disease (PD) brains, including accumulations of amyloid-β, phosphorylated tau, α-synuclein and parkin, as well as evidence of oxidative stress and mitochondrial abnormalities. Early-onset autosomal-recessive PD can be caused by mutations in the DJ-1 gene, leading to its inactivation. DJ-1 has anti-oxidative and mitochondrial-protective properties. In AD and PD brains, DJ-1 is increased and oxidized. We studied DJ-1 in 17 s-IBM and 18 disease-control and normal muscle biopsies by: 1) immunoblots of muscle homogenates and mitochondrial fractions; 2) real-time PCR; 3) oxyblots evaluating DJ-1 oxidation; 4) light- and electron-microscopic immunocytochemistry. Compared to controls, in s-IBM muscle fibers DJ-1 was: a) increased in the soluble fraction, monomer 2-fold (p=0.01), and dimer 2.8-fold (p=0.004); b) increased in the mitochondrial fraction; c) highly oxidized; and d) aggregated in about 15% of the abnormal muscle fibers. DJ-1 mRNA was increased 3.5-fold (p=0.034). Accordingly, DJ-1 might play a role in human muscle disease, and thus not be limited to human CNS degenerations. In s-IBM muscle fibers, DJ-1 could be protecting these fibers against oxidative stress, including protection of mitochondria. PMID:18601999

  6. Regulation of Reactive Oxygen Species and the Antioxidant Protein DJ-1 in Mastocytosis

    PubMed Central

    Kim, Do-Kyun; Beaven, Michael A.; Kulinski, Joseph M.; Desai, Avanti; Bandara, Geethani; Bai, Yun; Prussin, Calman; Schwartz, Lawrence B.; Komarow, Hirsh

    2016-01-01

    Neoplastic accumulation of mast cells in systemic mastocytosis (SM) associates with activating mutations in the receptor tyrosine kinase KIT. Constitutive activation of tyrosine kinase oncogenes has been linked to imbalances in oxidant/antioxidant mechanisms in other myeloproliferative disorders. However, the impact of KIT mutations on the redox status in SM and the potential therapeutic implications are not well understood. Here, we examined the regulation of reactive oxygen species (ROS) and of the antioxidant protein DJ-1 (PARK-7), which increases with cancer progression and acts to lessen oxidative damage to malignant cells, in relationship with SM severity. ROS levels were increased in both indolent (ISM) and aggressive variants of the disease (ASM). However, while DJ-1 levels were reduced in ISM with lower mast cell burden, they rose in ISM with higher mast cell burden and were significantly elevated in patients with ASM. Studies on mast cell lines revealed that activating KIT mutations induced constant ROS production and consequent DJ-1 oxidation and degradation that could explain the reduced levels of DJ-1 in the ISM population, while IL-6, a cytokine that increases with disease severity, caused a counteracting transcriptional induction of DJ-1 which would protect malignant mast cells from oxidative damage. A mouse model of mastocytosis recapitulated the biphasic changes in DJ-1 and the escalating IL-6, ROS and DJ-1 levels as mast cells accumulate, findings which were reversed with anti-IL-6 receptor blocking antibody. Our findings provide evidence of increased ROS and a biphasic regulation of the antioxidant DJ-1 in variants of SM and implicate IL-6 in DJ-1 induction and expansion of mast cells with KIT mutations. We propose consideration of IL-6 blockade as a potential adjunctive therapy in the treatment of patients with advanced mastocytosis, as it would reduce DJ-1 levels making mutation-positive mast cells vulnerable to oxidative damage. PMID:27611333

  7. A study on the expulsion of iodine from spent-fuel solutions

    SciTech Connect

    Sakurai, Tsutomu; Takahashi, Akira; Ishikawa, Niroh

    1995-02-01

    During dissolution of spent nuclear fuels, some radioiodine remains in spent-fuel solutions. Its expulsion to dissolver off-gas is important to minimize iodine escape to the environment. In our current work, the iodine remaining in spent-fuel solutions varied from 0 to 10% after dissolution of spent PWR-fuel specimens (approximately 3 g each). The amount remaining probably was dependent upon the dissolution time required. The cause is ascribable to the increased nitrous acid concentration that results from NOx generated during dissolution. The presence of nitrous acid was confirmed spectrophotometrically in an NO-HNO{sub 3} system at 100{degrees}C. Experiments examining NOx concentration versus the quantity of iodine in a simulated spent-fuel solution indicate that iodine (I{minus}) in spent fuels is subjected to the following three reactions: (1) oxidation into I{sub 2} by nitric acid, (2) oxidation into I{sub 2} by nitrous acid arising from NOx, and (3) formation of colloidal iodine (AgI, PdI{sub 2}), the major iodine species in a spent-fuel solution. Reaction (2) competes with reaction (3) to control the quantity of iodine remaining in solution. The following two-step expulsion process to remove iodine from a spent-fuel solution was derived from these experiments: Step One - Heat spent-fuel solutions without NOx sparging. When aged colloidal iodine is present, an excess amount of iodate should be added to the solution. Step Two - Sparge the fuel solution with NOx while heating. Effect of this new method was confirmed by use of a spent PWR-fuel solution.

  8. Thioredoxin-dependent redox regulation of chloroplastic phosphoglycerate kinase from Chlamydomonas reinhardtii.

    PubMed

    Morisse, Samuel; Michelet, Laure; Bedhomme, Mariette; Marchand, Christophe H; Calvaresi, Matteo; Trost, Paolo; Fermani, Simona; Zaffagnini, Mirko; Lemaire, Stéphane D

    2014-10-24

    In photosynthetic organisms, thioredoxin-dependent redox regulation is a well established mechanism involved in the control of a large number of cellular processes, including the Calvin-Benson cycle. Indeed, 4 of 11 enzymes of this cycle are activated in the light through dithiol/disulfide interchanges controlled by chloroplastic thioredoxin. Recently, several proteomics-based approaches suggested that not only four but all enzymes of the Calvin-Benson cycle may withstand redox regulation. Here, we characterized the redox features of the Calvin-Benson enzyme phosphoglycerate kinase (PGK1) from the eukaryotic green alga Chlamydomonas reinhardtii, and we show that C. reinhardtii PGK1 (CrPGK1) activity is inhibited by the formation of a single regulatory disulfide bond with a low midpoint redox potential (-335 mV at pH 7.9). CrPGK1 oxidation was found to affect the turnover number without altering the affinity for substrates, whereas the enzyme activation appeared to be specifically controlled by f-type thioredoxin. Using a combination of site-directed mutagenesis, thiol titration, mass spectrometry analyses, and three-dimensional modeling, the regulatory disulfide bond was shown to involve the not strictly conserved Cys(227) and Cys(361). Based on molecular mechanics calculation, the formation of the disulfide is proposed to impose structural constraints in the C-terminal domain of the enzyme that may lower its catalytic efficiency. It is therefore concluded that CrPGK1 might constitute an additional light-modulated Calvin-Benson cycle enzyme with a low activity in the dark and a TRX-dependent activation in the light. These results are also discussed from an evolutionary point of view. PMID:25202015

  9. Transgenesis of humanized fat1 promotes n-3 polyunsaturated fatty acid synthesis and expression of genes involved in lipid metabolism in goat cells.

    PubMed

    Fan, Yixuan; Ren, Caifang; Wang, Zhibo; Jia, Ruoxin; Wang, Dan; Zhang, Yanli; Zhang, Guomin; Wan, Yongjie; Huang, Mingrui; Wang, Feng

    2016-01-15

    The n-3 fatty acid desaturase gene fat1 codes for the n-3 desaturase enzyme, which can convert n-6 polyunsaturated fatty acids (PUFAs) to n-3 PUFAs. The n-3 PUFAs are essential components required for normal cellular function and have preventive and therapeutic effects on many diseases. Goat is an important domestic animal for human consumption of meat and milk. To elevate the concentrations of n-3 PUFAs and examine the regulatory mechanism of fat1 in PUFA metabolism in goat cells, we successfully constructed a humanized fat1 expression vector and confirmed the efficient expression of fat1 in goat ear skin-derived fibroblast cells (GEFCs) by qRT-PCR and Western blot analysis. Fatty acid analysis showed that fat1 overexpression significantly increased the levels of total n-3 PUFAs and decreased the levels of total n-6 PUFAs in GEFCs. In addition, qRT-PCR results indicate that the FADS1 and FADS2 desaturase genes, ELOV2 and ELOV5 elongase genes, ACO and CPT1 oxidation genes, and PPARa and PPARγ transcription factors are up-regulated, and transcription factors of SREBP-1c gene are down-regulated in the fat1 transgenic goat cells. Overall, fat1-overexpression resulted in an increase in the n-3 fatty acids and altered expression of PUFA synthesis related genes in GEFCs. This work lays a foundation for both the production of fat1 transgenic goats and further study of the mechanism of fat1 function in the PUFAs metabolism.

  10. Competitive Degradation of Steroid Estrogens by Potassium Permanganate Combined with Ultrasound.

    PubMed

    Deng, Jing; Tang, Kai; Zhu, Shijun; Ma, Xiaoyan; Zhang, Kejia; Song, Yali; Li, Xueyan; Li, Qingsong; Liu, Zhenhua; Zhou, Kejin

    2015-12-01

    The occurrence of natural estrogens including estrone (E1), 17β-estradiol (E2), and synthetic 17α-ethinylestradiol (EE2), which can be excreted by both humans and animals, and can enter the aqueous environment along with the discharge of domestic sewage, is a major concern since this may represent a serious health risk to humans even at extremely trace levels (ng·L(-1)). Simultaneous degradation of three coexisting steroid estrogens (SEs) in aqueous solutions by coupled ultrasound and KMnO₄ systems (KMnO₄/ultrasound) were investigated to find out whether there is a competitive degradation of multiple contaminants or not. Results indicate that the degradation ratios of target SEs were all more than 50% after 120 min reaction contact, greatly enhanced when compared with the single KMnO₄ (2 mg·L(-1)) oxidation of E2 (37.0%), EE2 (34.4%), and E1 (34.0%), and the single sonochemical oxidation of E2 (37.1%), EE2 (31.1%), and E1 (29.7%). In the adopted processes, the degradations of SEs fit the first-order kinetic reaction, with different reaction rates. Kinetic parameters revealed there was little difference between coexisting SEs, which means there was almost no competitive degradation. The removal efficiency and degradation rate of SEs in natural water was higher than those in pure water, which suggested that the coupled KMnO₄/ultrasound technology had prospective applications in the removal of complex contaminants in actual drinking water treatment. PMID:26690185

  11. Competitive Degradation of Steroid Estrogens by Potassium Permanganate Combined with Ultrasound.

    PubMed

    Deng, Jing; Tang, Kai; Zhu, Shijun; Ma, Xiaoyan; Zhang, Kejia; Song, Yali; Li, Xueyan; Li, Qingsong; Liu, Zhenhua; Zhou, Kejin

    2015-12-04

    The occurrence of natural estrogens including estrone (E1), 17β-estradiol (E2), and synthetic 17α-ethinylestradiol (EE2), which can be excreted by both humans and animals, and can enter the aqueous environment along with the discharge of domestic sewage, is a major concern since this may represent a serious health risk to humans even at extremely trace levels (ng·L(-1)). Simultaneous degradation of three coexisting steroid estrogens (SEs) in aqueous solutions by coupled ultrasound and KMnO₄ systems (KMnO₄/ultrasound) were investigated to find out whether there is a competitive degradation of multiple contaminants or not. Results indicate that the degradation ratios of target SEs were all more than 50% after 120 min reaction contact, greatly enhanced when compared with the single KMnO₄ (2 mg·L(-1)) oxidation of E2 (37.0%), EE2 (34.4%), and E1 (34.0%), and the single sonochemical oxidation of E2 (37.1%), EE2 (31.1%), and E1 (29.7%). In the adopted processes, the degradations of SEs fit the first-order kinetic reaction, with different reaction rates. Kinetic parameters revealed there was little difference between coexisting SEs, which means there was almost no competitive degradation. The removal efficiency and degradation rate of SEs in natural water was higher than those in pure water, which suggested that the coupled KMnO₄/ultrasound technology had prospective applications in the removal of complex contaminants in actual drinking water treatment.

  12. Isoniazid as a substrate and inhibitor of myeloperoxidase: identification of amine adducts and the influence of superoxide dismutase on their formation.

    PubMed

    Forbes, Louisa V; Furtmüller, Paul G; Khalilova, Irada; Turner, Rufus; Obinger, Christian; Kettle, Anthony J

    2012-10-01

    Neutrophils ingest Mycobacteria tuberculosis (Mtb) in the lungs of infected individuals. During phagocytosis they use myeloperoxidase (MPO) to catalyze production of hypochlorous acid (HOCl), their most potent antimicrobial agent. Isoniazid (INH), the foremost antibiotic in the treatment of tuberculosis, is oxidized by MPO. It rapidly reduced compound I of MPO [k = (1.22 ± 0.05) × 10(6) M(-1) s(-1)] but reacted less favorably with compound II [(9.8 ± 0.6) × 10(2) M(-1) s(-1)]. Oxidation of INH by MPO and hydrogen peroxide was unaffected by chloride, the physiological substrate for compound I, and the enzyme was partially converted to compound III. This indicates that INH is oxidized outside the classical peroxidation cycle. In combination with superoxide dismutase (SOD), MPO oxidized INH without exogenous hydrogen peroxide. SOD must favor reduction of oxygen by the INH radical to give superoxide and ultimately hydrogen peroxide. In both oxidation systems, an adduct with methionine was formed and it was a major product with MPO and SOD. We show that it is a conjugate of an acyldiimide with amines. INH substantially inhibited HOCl production by MPO and neutrophils below pharmacological concentrations. The reversible inhibition is explained by diversion of MPO to its ferrous and compound III forms during oxidation of INH. MPO, along with SOD released by Mtb, will oxidize INH at sites of infection and their interactions are likely to limit the efficacy of the drug, promote adverse drug reactions via formation of protein adducts, and impair a major bacterial killing mechanism of neutrophils.

  13. Antioxidant and antiradical activities of Manihot esculenta Crantz (Euphorbiaceae) leaves and other selected tropical green vegetables investigated on lipoperoxidation and phorbol-12-myristate-13-acetate (PMA) activated monocytes.

    PubMed

    Tsumbu, Cesar N; Deby-Dupont, Ginette; Tits, Monique; Angenot, Luc; Franck, Thierry; Serteyn, Didier; Mouithys-Mickalad, Ange

    2011-09-01

    Abelmoschus esculentus (Malvaceae), Hibiscus acetosella (Malvaceae), Manihot esculenta Crantz (Euphorbiaceae) and Pteridium aquilinum (Dennstaedtiaceae) leaves are currently consumed as vegetables by migrants from sub-Saharan Africa living in Western Europe and by the people in the origin countries, where these plants are also used in the folk medicine. Manihot leaves are also eaten in Latin America and some Asian countries. This work investigated the capacity of aqueous extracts prepared from those vegetables to inhibit the peroxidation of a linoleic acid emulsion. Short chain, volatile C-compounds as markers of advanced lipid peroxidation were measured by gas chromatography by following the ethylene production. The generation of lipid hydroperoxides, was monitored by spectroscopy using N-N'-dimethyl-p-phenylene-diamine (DMPD). The formation of intermediate peroxyl, and other free radicals, at the initiation of the lipid peroxidation was investigated by electron spin resonance, using α-(4-pyridyl-1-oxide)-N-tert-butylnitrone as spin trap agent. The ability of the extracts to decrease the cellular production of reactive oxygen species (ROS) in "inflammation like" conditions was studied by fluorescence technique using 2',7'-dichlorofluorescine-diacetate as fluorogenic probe, in a cell model of human monocytes (HL-60 cells) activated with phorbol ester. Overall the extracts displayed efficient concentration-dependent inhibitory effects. Their total polyphenol and flavonoid content was determined by classic colorimetric methods. An HPLC-UV/DAD analysis has clearly identified the presence of some polyphenolic compounds, which explains at least partially the inhibitions observed in our models. The role of these plants in the folk medicine by sub-Saharan peoples as well as in the prevention of oxidative stress and ROS related diseases requires further consideration. PMID:22254126

  14. Redox regulation of autophagy in healthy brain and neurodegeneration.

    PubMed

    Hensley, Kenneth; Harris-White, Marni E

    2015-12-01

    Autophagy and redox biochemistry are two major sub disciplines of cell biology which are both coming to be appreciated for their paramount importance in the etiology of neurodegenerative diseases including Alzheimer's disease (AD). Thus far, however, there has been relatively little exploration of the interface between autophagy and redox biology. Autophagy normally recycles macro-molecular aggregates produced through oxidative-stress mediated pathways, and also may reduce the mitochondrial production of reactive oxygen species through recycling of old and damaged mitochondria. Conversely, dysfunction in autophagy initiation, progression or clearance is evidenced to increase aggregation-prone proteins in neural and extraneural tissues. Redox mechanisms of autophagy regulation have been documented at the level of cross-talk between the Nrf2/Keap1 oxidant and electrophilic defense pathway and p62/sequestosome-1 (SQSTM1)-associated autophagy, at least in extraneural tissue; but other mechanisms of redox autophagy regulation doubtless remain to be discovered and the relevance of such processes to maintenance of neural homeostasis remains to be determined. This review summarizes current knowledge regarding the relationship of redox signaling, autophagy control, and oxidative stress as these phenomena relate to neurodegenerative disease. AD is specifically addressed as an example of the theme and as a promising indication for new therapies that act through engagement of autophagy pathways. To exemplify one such novel therapeutic entity, data is presented that the antioxidant and neurotrophic agent lanthionine ketimine-ethyl ester (LKE) affects autophagy pathway proteins including beclin-1 in the 3xTg-AD model of Alzheimer's disease where the compound has been shown to reduce pathological features and cognitive dysfunction.

  15. Key players of singlet oxygen-induced cell death in plants

    PubMed Central

    Laloi, Christophe; Havaux, Michel

    2015-01-01

    The production of reactive oxygen species (ROS) is an unavoidable consequence of oxygenic photosynthesis. Singlet oxygen (1O2) is a highly reactive species to which has been attributed a major destructive role during the execution of ROS-induced cell death in photosynthetic tissues exposed to excess light. The study of the specific biological activity of 1O2 in plants has been hindered by its high reactivity and short lifetime, the concurrent production of other ROS under photooxidative stress, and limited in vivo detection methods. However, during the last 15 years, the isolation and characterization of two 1O2-overproducing mutants in Arabidopsis thaliana, flu and ch1, has allowed the identification of genetically controlled 1O2 cell death pathways and a 1O2 acclimation pathway that are triggered at sub-cytotoxic concentrations of 1O2. The study of flu has revealed the control of cell death by the plastid proteins EXECUTER (EX)1 and EX2. In ch1, oxidized derivatives of β-carotene, such as β-cyclocitral and dihydroactinidiolide, have been identified as important upstream messengers in the 1O2 signaling pathway that leads to stress acclimation. In both the flu and ch1 mutants, phytohormones act as important promoters or inhibitors of cell death. In particular, jasmonate has emerged as a key player in the decision between acclimation and cell death in response to 1O2. Although the flu and ch1 mutants show many similarities, especially regarding their gene expression profiles, key differences, such as EXECUTER-independent cell death in ch1, have also been observed and will need further investigation to be fully understood. PMID:25699067

  16. Oxidant damage during and after spaceflight

    NASA Technical Reports Server (NTRS)

    Stein, T. P.; Leskiw, M. J.

    2000-01-01

    The objectives of this study were to assess oxidant damage during and after spaceflight and to compare the results against bed rest with 6 degrees head-down tilt. We measured the urinary excretion of the F(2) isoprostane, 8-iso-prostaglandin (PG) F(2alpha), and 8-oxo-7,8-dihydro-2 deoxyguanosine (8-OH DG) before, during, and after long-duration spaceflight (4-9 mo) on the Russian space station MIR, short-duration spaceflight on the shuttle, and 17 days of bed rest. Sample collections on MIR were obtained between 88 and 186 days in orbit. 8-iso-PGF(2alpha) and 8-OH DG are markers for oxidative damage to membrane lipids and DNA, respectively. Data are mean +/- SE. On MIR, isoprostane levels were decreased inflight (96. 9 +/- 11.6 vs. 76.7 +/- 14.9 ng. kg(-1). day(-1), P < 0.05, n = 6) due to decreased dietary intake secondary to impaired thermoregulation. Isoprostane excretion was increased postflight (245.7 +/- 55.8 ng. kg(-1). day(-1), P < 0.01). 8-OH DG excretion was unchanged with spaceflight and increased postflight (269 +/- 84 vs 442 +/- 180 ng. kg(-1). day(-1), P < 0.05). On the shuttle, 8-OH DG excretion was unchanged in- and postflight, but 8-iso-PGF(2alpha) excretion was decreased inflight (15.6 +/- 4.3 vs 8.0 +/- 2.7 ng. kg(-1). day(-1), P < 0.05). No changes were found with bed rest, but 8-iso-PGF(2alpha) was increased during the recovery phase (48.9 +/- 23.0 vs 65.4 +/- 28.3 ng. kg(-1). day(-1), P < 0.05). The changes in isoprostane production were attributed to decreased production of oxygen radicals from the electron transport chain due to the reduced energy intake inflight. The postflight increases in the excretion of the products of oxidative damage were attributed to a combination of an increase in metabolic activity and the loss of some host antioxidant defenses inflight. We conclude that 1) oxidative damage was decreased inflight, and 2) oxidative damage was increased postflight.

  17. Kinetics of cytochrome P450 2E1-catalyzed oxidation of ethanol to acetic acid via acetaldehyde.

    PubMed

    Bell-Parikh, L C; Guengerich, F P

    1999-08-20

    The P450 2E1-catalyzed oxidation of ethanol to acetaldehyde is characterized by a kinetic deuterium isotope effect that increases K(m) with no effect on k(cat), and rate-limiting product release has been proposed to account for the lack of an isotope effect on k(cat) (Bell, L. C., and Guengerich, F. P. (1997) J. Biol. Chem. 272, 29643-29651). Acetaldehyde is also a substrate for P450 2E1 oxidation to acetic acid, and k(cat)/K(m) for this reaction is at least 1 order of magnitude greater than that for ethanol oxidation to acetaldehyde. Acetic acid accounts for 90% of the products generated from ethanol in a 10-min reaction, and the contribution of this second oxidation has been overlooked in many previous studies. The noncompetitive intermolecular kinetic hydrogen isotope effects on acetaldehyde oxidation to acetic acid ((H)(k(cat)/K(m))/(D)(k(cat)/K(m)) = 4.5, and (D)k(cat) = 1.5) are comparable with the isotope effects typically observed for ethanol oxidation to acetaldehyde, and k(cat) is similar for both reactions, suggesting a possible common catalytic mechanism. Rapid quench kinetic experiments indicate that acetic acid is formed rapidly from added acetaldehyde (approximately 450 min(-1)) with burst kinetics. Pulse-chase experiments reveal that, at a subsaturating concentration of ethanol, approximately 90% of the acetaldehyde intermediate is directly converted to acetic acid without dissociation from the enzyme active site. Competition experiments suggest that P450 2E1 binds acetic acid and acetaldehyde with relatively high K(d) values, which preclude simple tight binding as an explanation for rate-limiting product release. The existence of a rate-determining step between product formation and release is postulated. Also proposed is a conformational change in P450 2E1 occurring during the course of oxidation and the discrimination of P450 2E1 between acetaldehyde and its hydrated form, the gem-diol. This multistep P450 reaction is characterized by kinetic

  18. Aqueous Alteration on Mars: Evidence from Landed Missions

    NASA Technical Reports Server (NTRS)

    Ming, Douglas W.; Morris, Richard V.; Clark, Benton C., III; Yen, Albert S.; Gellert, Ralf

    2015-01-01

    Mineralogical and geochemical data returned by orbiters and landers over the past 15 years have substantially enhanced our understanding of the history of aqueous alteration on Mars. Here, we summarize aqueous processes that have been implied from data collected by landed missions. Mars is a basaltic planet. The geochemistry of most materials has not been “extensively” altered by open-system aqueous processes and have average Mars crustal compositions. There are few examples of open-system alteration, such as Gale crater’s Pahrump Hills mudstone. Types of aqueous alteration include (1) acid-sulfate and (2) hydrolytic (circum-neutral/alkaline pH) with varying water-to-rock ratios. Several hypotheses have been suggested for acid-sulfate alteration including (1) oxidative weathering of ultramafic igneous rocks containing sulfides; (2) sulfuric acid weathering of basaltic materials; (3) acid fog weathering of basaltic materials; and (4) near-neutral pH subsurface solutions rich in Fe (sup 2 plus) that rapidly oxidized to Fe (sup 3 plus) producing excess acidity. Meridiani Planum’s sulfate-rich sedimentary deposit containing jarosite is the most “famous” acid-sulfate environment visited on Mars, although ferric sulfate-rich soils are common in Gusev crater’s Columbia Hills and jarosite was recently discovered in the Pahrump Hills. An example of aqueous alteration under circum-neutral pH conditions is the formation of Fe-saponite with magnetite in situ via aqueous alteration of olivine in Gale crater’s Sheepbed mudstone. Circum-neutral pH, hydrothermal conditions were likely required for the formation of Mg-Fe carbonate in the Columbia Hills. Diagenetic features (e.g., spherules, fracture filled veins) indicate multiple episodes of aqueous alteration/diagenesis in most sedimentary deposits. However, low water-to-rock ratios are prominent at most sites visited by landed missions (e.g., limited water for reaction to form crystalline phases possibly

  19. The Amyloid-β Peptide of Alzheimer’s Disease Binds CuI in a Linear Bis-His Coordination Environment: Insight into a Possible Neuroprotective Mechanism for the Amyloid-β Peptide

    SciTech Connect

    Shearer, J.; Szalai, V

    2008-01-01

    Oxidative stress has been suggested to contribute to neuronal apoptosis associated with Alzheimer's disease (AD). Copper may participate in oxidative stress through redox-cycling between its +2 and +1 oxidation states to generate reactive oxygen species (ROS). In vitro, copper binds to the amyloid-? peptide of AD, and in vivo, copper is associated with amyloid plaques characteristic of AD. As a result, the A?CuI complex may be a critical reactant involved in ROS associated with AD etiology. To characterize the A?CuI complex, we have pursued X-ray absorption (XAS) and electron paramagnetic resonance (EPR) spectroscopy of A?CuII and A?CuI (produced by ascorbate reduction of A?CuII). The A?CuII complex Cu K-edge XAS spectrum is indicative of a square-planar CuII center with mixed N/O ligation. Multiple scattering analysis of the extended X-ray absorption fine structure (EXAFS) data for A?CuII indicates that two of the ligands are imidazole groups of histidine ligands, indicating a (NIm)2(N/O)2 CuII ligation sphere for A?CuII. After reduction of the A?CuII complex with ascorbate, the edge region decreases in energy by 4 eV. The X-ray absorption near-edge spectrum region of A?CuI displays an intense pre-edge feature at 8984.1(2) eV. EXAFS data fitting yielded a two-coordinate geometry, with two imidazole ligands coordinated to CuI at 1.877(2) A in a linear geometry. Ascorbate reduction of A?CuII under inert atmosphere and subsequent air oxidation of A?CuI to regenerate A?CuII was monitored by low-temperature EPR spectroscopy. Slow reappearance of the A?CuII EPR signal indicates that O2 oxidation of the A?CuI complex is kinetically sluggish and A? damage is occurring following reoxidation of A?CuI by O2. Together, these results lead us to hypothesize that CuI is ligated by His13 and His14 in a linear coordination environment in ??, that A? may be playing a neuroprotective role, and that metal-mediated oxidative damage of A? occurs over multiple redox cycles.

  20. Spin trapping endogenous radicals in MC-1010 cells: evidence for hydroxyl radical and carbon-centered ascorbyl radical adducts.

    PubMed

    Bernofsky, C; Bandara, B M

    1995-07-19

    Incubation of MC-1010 cells with the spin-trapping agent 5,5-dimethyl-1-pyrroline 1-oxide (DMPO) followed by brief treatment with the solid oxidant lead dioxide (PbO2) yielded, after filtration, a cell-free solution that contained two nitroxyl adducts. The first was the hydroxyl radical adduct, 5,5-dimethyl-2-hydroxypyrrolidine-1-oxyl (DMPO-OH), which formed immediately upon PbO2 oxidation. The second had a 6-line EPR spectrum typical of a carbon-centered radical (AN = 15.9 G; AH = 22.4 G) and formed more slowly. No radical signals were detected in the absence of either cells or PbO2 treatment. The 6-line spectrum could be duplicated in model systems that contained ascorbate, DMPO and DMPO-OH, where the latter was formed from hydroxyl radicals generated by sonolysis or the cleavage of hydrogen peroxide with Fe2+ (Fenton reaction). In addition, enrichment of MC-1010 cells with ascorbate prior to spin trapping yielded the 6-line EPR spectrum as the principal adduct following PbO2 oxidation and filtration. These results suggest that ascorbate reacted with DMPO-OH to form a carbon-centered ascorbyl radical that was subsequently trapped by DMPO. The requirement for mild oxidation to detect the hydroxyl radical adduct suggests that DMPO-OH formed in the cells was reduced to an EPR-silent form (i.e., the hydroxylamine derivative). Alternatively, the hydroxylamine derivative was the species initially formed. The evidence for endogenous hydroxyl radical formation in unstimulated leukocytes may be relevant to the leukemic nature of the MC-1010 cell line. The spin trapping of the ascorbyl radical is the first report of formation of the carbon-centered ascorbyl radical by means other than pulse radiolysis. Unless it is spin trapped, the carbon-centered ascorbyl radical immediately rearranges to the more stable oxygen-centered species that is passive to spin trapping and characterized by the well-known EPR doublet of AH4 = 1.8 G.

  1. Meta-Regression Analyses, Meta-Analyses, and Trial Sequential Analyses of the Effects of Supplementation with Beta-Carotene, Vitamin A, and Vitamin E Singly or in Different Combinations on All-Cause Mortality: Do We Have Evidence for Lack of Harm?

    PubMed Central

    Bjelakovic, Goran; Nikolova, Dimitrinka; Gluud, Christian

    2013-01-01

    Background and Aims Evidence shows that antioxidant supplements may increase mortality. Our aims were to assess whether different doses of beta-carotene, vitamin A, and vitamin E affect mortality in primary and secondary prevention randomized clinical trials with low risk of bias. Methods The present study is based on our 2012 Cochrane systematic review analyzing beneficial and harmful effects of antioxidant supplements in adults. Using random-effects meta-analyses, meta-regression analyses, and trial sequential analyses, we examined the association between beta-carotene, vitamin A, and vitamin E, and mortality according to their daily doses and doses below and above the recommended daily allowances (RDA). Results We included 53 randomized trials with low risk of bias (241,883 participants, aged 18 to 103 years, 44.6% women) assessing beta-carotene, vitamin A, and vitamin E. Meta-regression analysis showed that the dose of vitamin A was significantly positively associated with all-cause mortality. Beta-carotene in a dose above 9.6 mg significantly increased mortality (relative risk (RR) 1.06, 95% confidence interval (CI) 1.02 to 1.09, I2 = 13%). Vitamin A in a dose above the RDA (> 800 µg) did not significantly influence mortality (RR 1.08, 95% CI 0.98 to 1.19, I2 = 53%). Vitamin E in a dose above the RDA (> 15 mg) significantly increased mortality (RR 1.03, 95% CI 1.00 to 1.05, I2 = 0%). Doses below the RDAs did not affect mortality, but data were sparse. Conclusions Beta-carotene and vitamin E in doses higher than the RDA seem to significantly increase mortality, whereas we lack information on vitamin A. Dose of vitamin A was significantly associated with increased mortality in meta-regression. We lack information on doses below the RDA. Background All essential compounds to stay healthy cannot be synthesized in our body. Therefore, these compounds must be taken through our diet or obtained in other ways [1]. Oxidative stress has been suggested to cause a

  2. Effects of Cobalt on Manganese Oxidation by Pseudomonas putida MnB1

    NASA Astrophysics Data System (ADS)

    Pena, J.; Bargar, J.; Sposito, G.

    2005-12-01

    The oxidation of Mn(II) in the environment is thought to occur predominantly through biologically mediated pathways. During the stationary phase of growth, the well-characterized freshwater and soil bacterium Pseudomonas putida MnB1 oxidizes soluble Mn(II) to a poorly crystalline layer type Mn(IV) oxide. These Mn oxide particles (2 - 5 nm thickness) are deposited in a matrix of extracellular polymeric substances (EPS) surrounding the cell, creating a multi-component system distinct from commonly studied synthetic Mn oxides. Accurate characterization of the reactivity of these biomineral assemblages is essential to understanding trace metal biogeochemistry in natural waters and sediments. Moreover, these biogenic oxides may potentially be used for the remediation of surface and ground waters impacted by mining, industrial pollution, and other anthropogenic activities. In this study, we consider the interactions between Co, P. putida MnB1, and its biogenic Mn oxide. Cobalt is a redox-active transition metal which exists in the environment as Co(II) and Co(III). While Co is not generally found in the environment at toxic concentrations, it may be released as a byproduct of mining activities (e.g. levels of up to 20 μM are found in Pinal Creek, AZ, a stream affected by copper mining). In addition, the radionuclide 60Co, formed by neutron activation in nuclear reactors, is of concern at Department of Energy sites, such as that at Hanford, and has several industrial applications, including radiotherapy. We address the following questions: Do high levels of Co inhibit enzymatic processes such as Mn(II) oxidation? Can the multicopper oxidase enzyme involved in Mn(II) oxidation facilitate Co(II) oxidation? Lastly, does the organic matter surrounding the oxides affect Co or Mn oxide reactivity? These issues were approached via wet chemical analysis, synchrotron radiation X-ray diffraction (SR-XRD), and extended X-ray absorption fine structure (EXAFS) spectroscopy. In the

  3. Macroscopic and molecular-scale assessment of soil lead contamination impacted by seasonal dove hunting activities

    SciTech Connect

    Arai, Y.; Tappero, R.; Rick, A.R.; Saylor, T.; Faas, E. & Lanzirotti, A.

    2011-05-24

    Environmental contamination of lead (Pb) in soils and sediments poses serious threats to human and ecological health. The objective of this study is to investigate the effect of seasonal dove sports hunting activities on Pb contamination in acid forest soils. A grid sampling method was used to investigate the spatial distribution of Pb contamination in surface soils. Soils were analyzed for total metal(loid) concentration and characterized for physicochemical properties and mineralogy. Adsorption isotherm experiments were also conducted to understand the reactivity and retention capacity of Pb(II) in soils. Finally, synchrotron-based X-ray microprobe and X-ray absorption spectroscopy were used to understand the chemical speciation of Pb that controls the retention/release mechanisms of Pb in soils. There was no excessive accumulation of Pb at the site. However, the concentration of Pb in surface soils was greater than the background level (<16 mg kg{sup -1}). The contamination level of Pb was as high as 67 mg kg{sup -1} near a patch of corn field where lime was frequently applied. A microfocused X-ray microprobe analysis showed the presence of Pb pellet fragments that predominantly contain oxidized Pb(II), suggesting that oxidative dissolution was occurring in soils. Dissolved Pb(II) can be readily retained in soils up to {approx}3,600 mg kg{sup -1} via inner-sphere and outer-sphere surface complexation on carbon and aluminol functional groups of soil components, suggesting that partitioning reactions control the concentration of Pb in soil solution. The fate of Pb is likely to be controlled by (1) oxidative dissolution process of Pb(0) pellets and (2) the release of outer-sphere and/or inner-sphere Pb surface complexes in humic substances and aluminosilicate/Al oxyhydroxides. Although no remedial actions are immediately required, the long-term accumulation of Pb in soils should be carefully monitored in protecting ecosystem and water quality at the dove hunting

  4. Expression and Characterization of CYP52 Genes Involved in the Biosynthesis of Sophorolipid and Alkane Metabolism from Starmerella bombicola

    PubMed Central

    Huang, Fong-Chin; Peter, Alyssa

    2014-01-01

    Three cytochrome P450 monooxygenase CYP52 gene family members were isolated from the sophorolipid-producing yeast Starmerella bombicola (former Candida bombicola), namely, CYP52E3, CYP52M1, and CYP52N1, and their open reading frames were cloned into the pYES2 vector for expression in Saccharomyces cerevisiae. The functions of the recombinant proteins were analyzed with a variety of alkane and fatty acid substrates using microsome proteins or a whole-cell system. CYP52M1 was found to oxidize C16 to C20 fatty acids preferentially. It converted oleic acid (C18:1) more efficiently than stearic acid (C18:0) and linoleic acid (C18:2) and much more effectively than α-linolenic acid (C18:3). No products were detected when C10 to C12 fatty acids were used as the substrates. Moreover, CYP52M1 hydroxylated fatty acids at their ω- and ω-1 positions. CYP52N1 oxidized C14 to C20 saturated and unsaturated fatty acids and preferentially oxidized palmitic acid, oleic acid, and linoleic acid. It only catalyzed ω-hydroxylation of fatty acids. Minor ω-hydroxylation activity against myristic acid, palmitic acid, palmitoleic acid, and oleic acid was shown for CYP52E3. Furthermore, the three P450s were coassayed with glucosyltransferase UGTA1. UGTA1 glycosylated all hydroxyl fatty acids generated by CYP52E3, CYP52M1, and CYP52N1. The transformation efficiency of fatty acids into glucolipids by CYP52M1/UGTA1 was much higher than those by CYP52N1/UGTA1 and CYP52E3/UGTA1. Taken together, CYP52M1 is demonstrated to be involved in the biosynthesis of sophorolipid, whereas CYP52E3 and CYP52N1 might be involved in alkane metabolism in S. bombicola but downstream of the initial oxidation steps. PMID:24242247

  5. The mechanism of the modified Ullmann reaction.

    PubMed

    Sperotto, Elena; van Klink, Gerard P M; van Koten, Gerard; de Vries, Johannes G

    2010-11-21

    The copper-mediated aromatic nucleophilic substitution reactions developed by Fritz Ullmann and Irma Goldberg required stoichiometric amounts of copper and very high reaction temperatures. Recently, it was found that addition of relatively cheap ligands (diamines, aminoalcohols, diketones, diols) made these reactions truly catalytic, with catalyst amounts as low as 1 mol% or even lower. Since these catalysts are homogeneous, it has opened up the possibility to investigate the mechanism of these modified Ullmann reactions. Most authors agree that Cu(I) is the true catalyst even though Cu(0) and Cu(II) catalysts have also shown to be active. It should be noted however that Cu(I) is capable of reversible disproportionation into Cu(0) and Cu(II). In the first step, the nucleophile displaces the halide in the LnCu(I)X complex forming LnCu(I)ZR (Z = O, NR′, S). Quite a number of mechanisms have been proposed for the actual reaction of this complex with the aryl halide: 1. Oxidative addition of ArX forming a Cu(III) intermediate followed by reductive elimination; 2. Sigma bond metathesis; in this mechanism copper remains in the Cu(II) oxidation state; 3. Single electron transfer (SET) in which a radical anion of the aryl halide is formed (Cu(I)/Cu(II)); 4. Iodine atom transfer (IAT) to give the aryl radical (Cu(I)/Cu(II)); 5. π-complexation of the aryl halide with the Cu(I) complex, which is thought to enable the nucleophilic substitution reaction. Initially, the radical type mechanisms 3 and 4 where discounted based on the fact that radical clock-type experiments with ortho-allyl aryl halides failed to give the cyclised products. However, a recent DFT study by Houk, Buchwald and co-workers shows that the modified Ullmann reaction between aryl iodide and amines or primary alcohols proceeds either via an SET or an IAT mechanism. Van Koten has shown that stalled aminations can be rejuvenated by the addition of Cu(0), which serves to reduce the formed Cu(II) to Cu

  6. Possible role of bacterial siderophores in inflammation. Iron bound to the Pseudomonas siderophore pyochelin can function as a hydroxyl radical catalyst.

    PubMed Central

    Coffman, T J; Cox, C D; Edeker, B L; Britigan, B E

    1990-01-01

    Tissue injury has been linked to neutrophil associated hydroxyl radical (.OH) generation, a process that requires an exogenous transition metal catalyst such as iron. In vivo most iron is bound in a noncatalytic form. To obtain iron required for growth, many bacteria secrete iron chelators (siderophores). Since Pseudomonas aeruginosa infections are associated with considerable tissue destruction, we examined whether iron bound to the Pseudomonas siderophores pyochelin (PCH) and pyoverdin (PVD) could act as .OH catalysts. Purified PCH and PVD were iron loaded (Fe-PCH, Fe-PVD) and added to a hypoxanthine/xanthine oxidase superoxide- (.O2-) and hydrogen peroxide (H2O2)-generating system. Evidence for .OH generation was then sought using two different spin-trapping agents (5.5 dimethyl-pyrroline-1-oxide or N-t-butyl-alpha-phenylnitrone), as well as the deoxyribose oxidation assay. Regardless of methodology, .OH generation was detected in the presence of Fe-PCH but not Fe-PVD. Inhibition of the process by catalase and/or SOD suggested .OH formation with Fe-PCH occurred via the Haber-Weiss reaction. Similar results were obtained when stimulated neutrophils were used as the source of .O2- and H2O2. Addition of Fe-PCH but not Fe-PVD to stimulated neutrophils yielded .OH as detected by the above assay systems. Since PCH and PVD bind ferric (Fe3+) but not ferrous (Fe2+) iron, .OH catalysis with Fe-PCH would likely involve .O2(-)-mediated reduction of Fe3+ to Fe2+ with subsequent release of "free" Fe2+. This was confirmed by measuring formation of the Fe2(+)-ferrozine complex after exposure of Fe-PCH, but not Fe-PVD, to enzymatically generated .O2-. These data show that Fe-PCH, but not Fe-PVD, is capable of catalyzing generation of .OH. Such a process could represent as yet another mechanism of tissue injury at sites of infection with P. aeruginosa. PMID:2170442

  7. The amyloid-β peptide of Alzheimer's disease binds CuI in a linear bis-His coordination environment: Insight into a possible neuroprotective mechanism for the amyloid-β peptide

    PubMed Central

    2010-01-01

    Oxidative stress has been suggested to contribute to neuronal apoptosis associated with Alzheimer's disease (AD). Copper may participate in oxidative stress through redox-cycling between its +2 and +1 oxidation states to generate reactive oxygen species (ROS). In vitro, copper binds to the amyloid-β peptide of AD and in vivo, copper is associated with amyloid plaques characteristic of AD. As a result, the AβCuI complex may be a critical reactant involved in ROS associated with AD etiology. To characterize the AβCuI complex, we have pursued X-ray absorption (XAS) and EPR spectroscopy of AβCuII and AβCuI (produced by ascorbate reduction of AβCuII). The AβCuII complex Cu K-edge X-ray absorption spectrum is indicative of a square-planar CuII center wit